· web viewthe periodic table is a list of all the known elements. it is organized by increasing...

Chemistry Unit 2-2: Matter and Atomic Theory

Name:_________________________ Period:__________www.beiermanchem.com

DATE TOPIC/ACTIVITY HOMEWORK

Monday9/23LATE START

1. Bohr and the Quantum Mechanical Model of the atom

2. Valence Electron Worksheet

Finish Valence Electron Worksheet and Bohr Worksheet

Tuesday9/24

1. Energy and Light Notes Video Notes: Periodic Table

Wednesday9/25

BEIERMAN ABSENT1. Periodic Table Notes2. Color areas of the periodic table

Periodic Table Worksheets 1 & 2

Thursday9/26

1. Electron Configuration Notes2. Electron Configuration and Orbital

Diagram Worksheet #1

Finish Electron Configuration Worksheet

Friday9/27 NO SCHOOL!

Monday9/30

3. Continue Electron Configuration and Orbital Diagram

Tuesday10/1

1. Lewis Dot Notes Finish Lewis Dot Worksheet

Wednesday10/2

BEIERMAN ABSENT1. Coulombic Attraction Activity

Video Notes: Periodic Trends

Finish Worksheet

Thursday10/3

1. Periodic Trends Lab

Friday10/4

1. Periodic Trends Continued

Monday10/7

REVIEW

Tuesday10/8 TEST

1

http://www.beiermanchem.com/


2


Key Ideas The placement or location of elements on the Periodic Table gives an indication of physical and

chemical properties of that element. The elements on the Periodic Table are arranged in order of increasing atomic number.

Elements can be classified by their properties and located on the Periodic Table as metals, nonmetals, metalloids (B, Si, Ge, As, Sb, Te), and noble gases.

Elements can be differentiated by their physical properties. Physical properties of substances, such as density, conductivity, malleability, solubility, and hardness, differ among elements.

Elements can be differentiated by chemical properties. Chemical properties describe how an element behaves during a chemical reaction.

Some elements exist in two or more forms in the same phase. These forms differ in their molecular or crystal structure, and hence in their properties.

For Groups 1, 2, and 13-18 on the Periodic Table, elements within the same group have the same number of valence electrons (helium is an exception) and therefore similar chemical properties.

The succession of elements within the same group demonstrates characteristic trends: differences in atomic radius, ionic radius, electronegativity, first ionization energy, metallic/nonmetallic properties.

In the wave-mechanical model (electron cloud model), the electrons are in orbitals, which are defined as the regions of the most probable electron location (ground state).

Each electron in an atom has its own distinct amount of energy.

When an electron in an atom gains a specific amount of energy, the electron is at a higher energy state (excited state).

When an electron returns from a higher energy state to a lower energy state, a specific amount of energy is emitted. This emitted energy can be used to identify an element.

The outermost electrons in an atom are called the valence electrons. In general, the number of valence electrons affects the chemical properties of an element.

The placement or location of elements on the Periodic Table gives an indication of physical and chemical properties of that element. The elements on the Periodic Table are arranged in order of increasing atomic number.

For Groups 1, 2, and 13-18 on the Periodic Table, elements within the same group have the same number of valence electrons (helium is an exception) and therefore similar chemical properties.

NOTES

3


I. Quantum Model of the AtomA. Electrons as Waves

1. Louis de Broglie (1924) proposed that electrons have wavelike properties

B. Heisenberg Uncertainty Principle – it is impossible to determine both the position and the path of the electron at the same time1. electrons are detected by their interaction with photons2. because electrons are so small, an attempt to locate an electron with a photon

knocks the electron off its course

C. Schrodinger Wave Equation1. Erwin Schrodinger (1927) developed a mathematical equation that treated electrons

as waves2. electrons do not travel in exact orbits; instead they exist in certain regions of space

called orbitals

D. Atomic Orbitals and Quantum Numbers1. a set of four quantum numbers describes the properties of an atomic orbital

2. Quantum Number Describesa. principal (n) energy levelb. angular momentum (l) shape of orbital (sublevel)c. magnetic (m) orientation in space (orbital)d. spin spin of electron

E. The order of the orbitals is 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p

a. The s orbital is sphere shaped and there are 7.b. The p orbital is lobed or dumbbell shaped and there are 6. c. The d and f orbitals shapes are hard to define. There are 4 d orbitals 2 f

orbitals.

F. Orbital Shapes

II. Electron Configurations

4


A. Electron configuration – the arrangement of the electrons in an atom. The position or space the electron is in around the nucleus.

B. Rules for Electron Configurations1. Aufbau principle – an electron occupies the lowest energy orbital that is available

2. Pauli Exclusion Principle – an orbital may contain 2 electrons which have opposite spin

3. Hund’s Rule – one electron enters each orbital in a sublevel before a second electron enters any of them

4. Valence electrons – electrons in the outer most orbital. These electrons are the ones involved in bonding.

Valence Electrons

5


The valence electrons are the electrons in the outermost energy level.

Since the maximum number of electrons possible in the orbitals is eight, there can be no more than eight valence electrons.

Valence electrons determine how an element behaves, as elements with four or more valence electrons want to react with other elements to gain electrons to get a full valence shell.

Elements with 3 or less valence electrons will react with other elements to lose electrons to get to a full valence shell.

Determine the element’s number of valence electrons (# of electrons in the “outermost” shell).

Example: Carbon has 4 valence electrons, carbon__4__

1. fluorine _____ 10. lithium _____2. phosphorus _____ 11. sulfur _____3. calcium _____ 12. carbon _____4. nitrogen _____ 13. iodine _____5. oxygen _____ 14. xenon _____6. argon _____ 15. barium _____7. potassium _____ 16. aluminum _____8. helium _____ 17. hydrogen _____9. magnesium _____

1. What are valence electrons used for by an element?

2. Which elements listed above want to lose electrons? What type of elements are they?

3. Which elements above want to gain electrons? What type of elements are they?

4. Why do the elements from question 2 want to lose electrons? Why do the elements from question 3 want to gain electrons? (The answer is the same for both questions).

5. How many valence electrons do the elements in group 18 have? Would these elements react with other elements? Explain your answer.

Bohr Diagrams

6


Bohr diagrams show the number of protons and neutrons in the nucleus and the number of electrons in their energy levels. The electron configuration shows how many electrons are in each level in the ground state, or under normal conditions. An example of a Bohr diagram is given below:

Draw the Bohr diagrams of the following:

H-1 K-40 Li-7 Be-9

B-11 C-14 Ne-20 O-16

F-19 Cl-35 Al-27 S-28

S-32 N-14 Mg-24 P-31

Valence electrons are the electrons in the outermost shell. They are the furthest from the nucleus, escaping the protons pulling on them. Therefore, they have the __________ energy out of all the electrons. Do any of the elements above have the same number of valence electrons? List the pairs:

7


Light Waves

The behavior of light indicates that it is comprised of waves. The distance between successive waves is called the wavelength (Z) and the wavelength determines the type of light. The size of the waves determines the type of light. All of the various light waves move with the same speed, a value abbreviated (c) equal to 3.00 × 108 m/s. The frequency (u) that light waves pass a given point is measured in waves/second or simply ‘per second’ (1/s). The unit 1/s is also given the name hertz (Hz).

Answer the following questions about light waves. Show all work

1. What type of light has a wavelength of: a) 5.0 × 10-4 m? b) 2.4 × 10-8 m? c)12 mm?

2. An ultraviolet light wave is used to kill bacterial. It has a frequency of 1.2 × 1015 1/s. Find the wavelength.

3. An x-ray has a wavelength of 1.54 × 10-10 m. Find the frequency of this light.

4. A visible light wave has a frequency of 7.5 × 1014 1/s. Find the wavelength in nanometers (nm) and determine the color of the light.

5. One of the light waves produced when hydrogen is energized has a wavelength of 410.5 nm. What is the frequency of this light?

6. The frequency of light used to heat food in a microwave oven is 2.45 GHz (2.45 × 109 1/s). What is the wavelength of this light?

8


7. A radio wave broadcast on the AM dial has a wavelength of 280.4 m. Find the frequency of this radio wave in hertz. Convert the frequency to kilohertz.

8. What is the wavelength of a radio wave broadcast with a frequency of 99.5 MHz (FM 99.5)?

9. Pilots often use waves of about 2.340 m to communicate. What is the frequency of this wave?

10. The light used in night vision devices has a wavelength of about 25 micrometers (µm). What is the frequency of this light? In what part of the electromagnetic spectrum are these waves?

Color Coding the Periodic Table Activity

9


The Periodic Table is a list of all the known elements. It is organized by increasing atomic number. There are two main groups on the periodic table: metals and nonmetals. The left side of the table contains elements with the greatest metallic properties. As you move from the left to the right, the elements become less metallic with the far right side of the table consisting of nonmetals. A small group of elements, whose members touch the zigzag line, are called metalloids because they have both metallic and nonmetallic properties. Identify the zig zag line and make it more bold using a black crayon.

The table is also arranged in vertical columns called “groups” or “families” and horizontal rows called “periods.” Each arrangement is significant. The elements in each vertical column or group have similar properties. There are a number of major groups with similar properties. They are as follows:

Hydrogen: This element does not match the properties of any other group so it stands alone. It is placed above group 1 but it is not part of that group. It is a very reactive, colorless, odorless gas at room temperature. (1 outer level electron) Outline Hydrogen in red.

Group 1: Alkali Metals – These metals are extremely reactive and are never found in nature in their pure form. They are silver colored and shiny. Their density is extremely low so that they are soft enough to be cut with a knife. (1 outer level electron) Color the alkali metals in red.

Group 2: Alkaline-earth Metals – Slightly less reactive than alkali metals. They are silver colored and more dense than alkali metals. (2 outer level electrons) Color the alkaline earth metals in orange.

Groups 3 – 12: Transition Metals – These metals have a moderate range of reactivity and a wide range of properties. In general, they are shiny and good conductors of heat and electricity. They also have higher densities and melting points than groups 1 & 2. (1 or 2 outer level electrons) Color the transition metals in pink.

Lanthanides and Actinides: These are also transition metals that were taken out and placed at the bottom of the table so the table wouldn’t be so wide. The elements in each of these two periods share many properties. The lanthanides are shiny and reactive. The actinides are all radioactive and are therefore unstable. Elements 95 through 103 do not exist in nature but have been manufactured in the lab. Color the lanthanides and actinides brown.

Group 13: Boron Group – Contains one metalloid and 4 metals. Reactive. Aluminum is in this group. It is also the most abundant metal in the earth’s crust. (3 outer level electrons) Color group 13 yellow.

Group 14: Carbon Group – Contains on nonmetal, two metalloids, and two metals. Varied reactivity. (4 outer level electrons) Color group 14 light green.

Group 15: Nitrogen Group – Contains two nonmetals, two metalloids, and one metal. Varied reactivity. (5 outer level electrons) Color group 15 dark green.

Group 16: Oxygen Group – Contains three nonmetals, one metalloid, and one metal. Reactive group. (6 outer level electrons) Color group 16 light blue.

Group 17: Halogens – All nonmetals. Very reactive. Poor conductors of heat and electricity. Tend to form salts with metals. Ex. NaCl: sodium chloride also known as “table salt”. (7 outer level electrons) Color group 17 dark blue.

10


Group 18: Noble Gases – Unreactive nonmetals. All are colorless, odorless gases at room temperature. All found in earth’s atmosphere in small amounts. (8 outer level electrons) Color group 18 Purple.

Analysis:

1. The vertical columns on the periodic table are called ____________.

2. The horizontal rows on the periodic table are called _____________.

3. Most of the elements in the periodic table are classified as _____________.

4. The elements that touch the zigzag line are classified as _______________.

5. The elements in the far upper right corner are classified as______________.

6. Elements in the first group have one outer shell electron and are extremely reactive. They are called

7. Elements in the second group have 2 outer shell electrons and are also very reactive. They are called

8. Elements in groups 3 through 12 have many useful properties and are called ____________________.

9. Elements in group 17 are known as “salt formers”. They are called _________________.

10. Elements in group 18 are very unreactive. They are said to be “inert”. We call these the ____________.

11. The elements at the bottom of the table were pulled out to keep the table from becoming too long. The

first period at the bottom called the _________________.

12. The second period at the bottom of the table is called the _____________________.

13. What are valence Electrons?

11


Periods and Groups

Introduction

Look at the periodic table of elements. 12


1. Periods represent the (vertical/horizontal) rows on the table. 2. Draw Bohr diagrams for Carbon, Boron and Oxygen, all in period 2.

3. Elements in the same period have the same number of ______________________. 4. Groups represent the (vertical/horizontal) columns on the table. 5. Draw Bohr diagrams for Lithium, Sodium, and Potassium, all in group 1.

6. Elements in the same group have the same number of ______________________. 7.8. RULES: Group 1 are known as Alkali Metals. Group 2 are Alkaline earth metals. Groups 3-12 are

Transition metals. Group 17 are Halogens. Group 18 are Noble gases. All other groups do not have names.

Name Symbol Period # Energy Levels

Group # Valence Electrons Group Name

Sodium

S

Ne

1 Noble Gases

2 2

2 Alkali Metals

4 1

4 7

4 Alkaline EarthMetals

2 Halogens

3 8

Period and Groups Summary

Look at the periodic table of elements.

13


1. How many periods are on the periodic table of elements?

2. Write out electron configurations for one of the elements in period 3.

3. What do elements in the same period have in common?

4. How many groups are on the periodic table of elements?

5. Write out Lewis dot diagrams for one of the elements in group 18.

6. Write out the most probable charges of elements in group:

a. One___ b. Two___ c. Seventeen____ d. Eighteen___

7. What do elements in the same group have in common?

8. Do elements in the same period have more or less in common than elements in the same group?

1. Which three groups of the Periodic Table contain the most elements classified as metalloids (semimetals)?A) 1, 2, and 13 B) 2, 13, and 14C) 14, 15, and 16 D) 16, 17, and 18

2. Which elements have the most similar chemical properties?A) K and Na B) K and ClC) K and Ca D) K and S

14

Chemistry Unit 2-2: Matter and Atomic Theory3. The metalloids that are included in Group 15 are antimony and(A) N B) P C) As D) Bi

4. Which element is a member of the halogen family?(A) K B) B C) I D) S

5. An atom of an element contains 20 protons, 20 neutrons, and 20 electrons. This element is in GroupA) 1 B) 2 C) 4 D) 18

6. Which sequence of atomic numbers represents elements which have similar chemical properties?A) 19, 23, 30, 36 B) 9, 16, 33, 50C) 3, 12, 21, 40 D) 4, 20, 38, 88

7. Alkali metals, alkaline earth metals, and halogens are elements found respectively in GroupsA) 1, 2, and 18 B) 2, 13, and 17C) 1, 2, and 14 D) 1, 2, and 17

8. Which group contains elements composed of diatomic molecules at STP?A) 11 B) 2 C) 7 D) 17

9. On the Periodic Table, an element classified as a semimetal (metalloid) can be found in(A) Period 6, Group 15 B) Period 2, Group 14C) Period 3, Group 16 D) Period 4, Group 15

10. Atoms of metallic elements tend to(A) gain electrons and form negative ions(B) gain electrons and form positive ions(C) lose electrons and form negative ions(D) lose electrons and form positive ions

Which element is considered malleable?(A) gold B) hydrogen(C) sulfur D) radon

Which element is malleable and conducts electricity?(A) iron B) iodineC) sulfur D) phosphorus

11. Which element is malleable and ductile?S B) Si C) Ge D) Au

12. Which element is brittle and does not conduct heat or electricity?

S(s) B) Mg(s) C) Al(s) D) K(s)

13. Which element is an active nonmetal?Neon B) oxygen C) zinc D) chromium

14. Which characteristics describe most solid nonmetals?They are malleable and have metallic luster.They are malleable and lack metallic luster.They are brittle and have metallic luster.They are brittle and lack metallic luster.

15. An atom in the ground state has a stable valence electron configuration. This atom could be an atom ofAl B) Cl C) Na D) Ne

16. Which element at STP exists as monatomic molecules?(A) N B) O C) Cl D) Ne

17. Which element is a metalloid?(A) Al B) Ar C) As D) Au

18.The element arsenic (As) has the properties of(A) metals, only(B) nonmetals, only(C) both metals and nonmetals(D) neither metals nor nonmetals

19. Which element is not a metalloid?(A) arsenic B) boronC) silicon D) sulfur

20. An atom in the ground state contains a total of 5 electrons, 5 protons, and 5 neutrons. Which Lewis electron-dot diagram represents this atom?

A) B) C) D)

21. Magnesium and calcium have similar chemical properties because a magnesium atom and a calcium atom have the same(A) atomic numbermass numbertotal number of electron shellstotal number of valence electrons

Which compound forms a green aqueous solution?RbCl B) CaCl2 C) NiCl2 D) MgCl2

Orbital Diagrams Worksheet #1

An orbital diagram uses boxes with arrows to represent the electrons in an atom. Each box in an orbital diagram represents an orbital. Orbitals have a capacity of two electrons. Arrows are drawn inside the boxes to represent electrons. Two electrons in the same orbital

15


must have opposite spin so the arrows are drawn pointing in opposite directions. The following is an orbital diagram for selenium.

In writing an orbital diagram the first step is to determine the number of electrons. Normally this is the same as the number of protons, which is known as the atomic number. Next the boxes are drawn for the orbitals. Arrows are drawn in the boxes starting from the lowest energy sublevel and working up. This is known as the Aufbau rule. The Pauli exclusion principle requires that electrons in the same orbital have opposite spin. Hund’s rule states orbitals in a given sublevel are half-filled before they are completely filled.

Write orbital diagrams for the following. You may abbreviate using a noble gas.7. Hydrogen

8. Boron

16


9. Sodium

10. Krypton

11. Chromium

12. Phosphorus

13. Carbon

14. Cobalt

15. Platinum

16. Oxygen

17. Potassium

Electron ConfigurationAn electron configuration is simply a list of the orbitals that contain electrons for a given

element. The orbital designation is followed by a superscript number that tells how many electrons are found in that orbital. The following designation represents an atom with electrons found in the 1s, the 2s, the 2p,

17


and the 3s orbitals. There are a total of 11 electrons in the atom. This represents the element sodium.

The orbitals of an atom fill in a specific sequence. The pattern fits very nicely with various regions of the periodic table. The table is been sectioned into blocks which are labeled: s block, p block, d block, and f block. The rows of each block are labeled as well. Using this shortcut, electron configurations can be determined easily. The element manganese is the fifth element in the 3d row. The orbitals before the 3d orbital are all filled so it has full 1s, 2s, 2p, 3s, 3p, and 4s orbitals. Since manganese is the fifth element in the 3d row we designate the 3d orbital with 5 electrons.

Electron configurations can be abbreviated by writing the element symbol for the previous noble gas in brackets, followed by the remaining electrons. For example, rather than writing all of the electrons in antimony (element 51), the first 36 electrons are represented by [Kr]. The remaining electrons are notated using orbital names and superscript numbers.

18


Lewis Diagrams

19


The outermost electrons in an atom are called the valence electrons. These electrons are especially important because they interact with other atoms in chemical bonds. The valence electrons are those electrons in the highest energy level. When the electron configuration is known, the number of valence electrons can be determined by adding up the electrons found in the highest energy s and p orbitals. The number of valence electrons can also be determined by simply determining the group number on the periodic table. The last digit of the group number indicates the number of valence electrons.

A system of tracking valence electrons was developed by G. N. Lewis. In this system the element symbol is written to represent an atom and dots are written around the symbol to represent valence electrons. The dots are generally spaced out evenly. Since the largest number of valence electrons for the representative elements (those in the s or p block) is eight, we place a maximum of two dots on each side.

Use your periodic table to answer the following questions.

1. Tin has valence electrons, and chlorine has valence electrons.

2. Three atoms that have eight valence electrons are , , and .

3. Each of the atoms in alkali earth metal family (group 2) has valence electrons.

4. Sodium has valence electrons, and bismuth has valence electrons.

5. The valence electrons are those found in the highest energy and orbitals.

6. How many dots are drawn in the Lewis dot diagram for phosphorus?

7. Iodine has seven valence electrons. Which other elements have seven valence electrons?

8. An element with the electron configuration: [Xe] 6s24f145d106p2 has how many valence electrons?

20


Write the electron dot (Lewis) diagrams for the following.

21


Extra Lewis Dot Practice

Lewis diagrams show only the atom’s symbol and dots representing the valence electrons. The most valence electrons an atom can have is ____ so the most dots you will draw is ____. Please make dots very visible!

Examples:

Name Protons Neutrons ElectronsValence

ElectronsLewis

Diagram

Rubidium-85

Cesium-133

Strontium-88

Barium-138

Germanium-72

Tin-119

Arsenic-75

Antimony-121

Sellenium-79

Tellurium-127

Bromine-80

Iodine-127

Xenon-131

Krypton -84

22


1. Why are the valence electrons the most important electrons? __________________________

2. What do elements with the same valence electrons have in common?

___________________________________________________________________________

3. The kernel electrons are all electrons except the valence electrons. How many kernel

electrons does magnesium have?

___________________________________________________________________________

4. Draw the Lewis dot diagram of Li+, Ca+2, S-2 and F-

5. All cations have _________ dots and all anions have _______ dots.

6. Explain why arsenic can form three different ions in terms of valence electrons and stability.

7. Explain why more transition metals have two valence electrons with the exception of groups 6

and 11.

23


Coulombic Forces

Distance and Force of Attraction

1. What subatomic particles do these symbols represent in Model 1?

–

2. Do you think the particles will attract or repel each other?

3. If the distance between a proton and electron is 0.50 nm, would you expect the force of attraction to be greater than or less than 0.26 × 10–8 N?

4. If two protons are 0.10 nm away from one electron, would you expect the force of attraction to be greater than or less than 2.30 × 10–8 N?

Alkali Metals

24

+++++++++++++++++++++++++++++++++


1. What do the arrows represent?

2. How does the thickness of the arrows relate to force?

3. Using a periodic table, locate the elements whose atoms are drawn above. Are the elements in the same column or the same row?

4. Circle the outermost electrons in each diagram. As you move from the smallest atom to the largest atom in Model 2, how does the distance between the outermost electron and the nucleus change?

a. As you move from the smallest atom to the largest atom in Model 2, how does the attractive force between the outermost electron and the nucleus change?

b. As you move from the smallest atom to the largest atom in Model 2, how does the attractive force between the outermost electron and the nucleus change?

Number of Protons and Attractive Forces

25


1. What would be the attractive force on a single electron if five protons were in the nucleus of an atom? Show mathematical work to support your answer.

2. Imagine that a second electron were placed to the left of a nucleus containing two protons (Model 3, set D). Predict the force of attraction on both the original electron and the second electron. Explain your prediction with a complete sentence.

NOTE: The attractive and repulsive forces in an atom are rather complex. An electron is attracted to the protons in the nucleus, but it is also repelled by the other electrons in the atom. It is important to note however that the attractive force of the nucleus is NOT divided up among the electrons in the atom. Each electron gets approximately the full attractive force of the nucleus (minus the repulsive effects of other electrons). Compare the diagram below to set D in Model 3. Notice the similarity in attractive force.

26


1. Using the periodic table, locate the elements whose atoms are drawn above. Are the elements in the same column or the same row?

2. Circle the outermost electron(s) in each of the atoms in the above models.

3. Which of the three atoms diagrammed in the above models has the strongest attraction for its outermost electron(s)?

4. As you move from the smallest atom to the largest atom, does the distance between the outermost electron(s) and the nucleus change significantly?

5. Can the differences in the attractive force shown by the arrows be explained by a change in the distance between the electron(s) and the nucleus?

6. On the diagrams above, write the number of protons located in the nucleus of each atom.

7. Can the differences in attractive forces shown by the arrows in the model be explained by a change in the number of protons in the nucleus? If yes, explain the relationship.

27


Periodic Trends Lab

Summarize the following periodic trends:

1. Coulombic Attraction

2. Atomic Radius

3. Ionization Energy

4. Electronegativity

5. Reactivity

28

· web viewthe periodic table is a list of all the known elements. it is organized by increasing...

Documents