Ch. 4 section 1 Notes

11-1-11Item #53/56 honors

Atoms Atom = is the smallest particle of an

element Existence theorized and named by

Democritus in 4th century B.C.! Atomic Theory grew as a series of

models developed from experimental evidence, over time the theories and models were revised

Dalton’s Atomic Theory In 1808 Dalton developed the atomic

theory: Atoms cannot be divided (now false) All atoms of one element are exactly alike

(now false) Atoms cannot be changed into an atom of a

different element. Atoms cannot be created nor destroyed, only rearranged.

Atoms of different elements join in specific ratios to form compounds

The next 4 slides are for your information…you do not need to write down

Thompson’s Model In 1897, Thompson

discovered the electron, a negatively charged particle within an atom.

Proposed model of atom with negative charges scattered throughout a ball of positive charge – like berries in a muffin.

Rutherford’s Model In 1911,

Rutherford used his gold foil experiment to find the nucleus, a tiny region in the center which contained positively charged protons.

Bohr’s Model

In 1913, Bohr showed the electrons moved in orbits like planets orbiting around the sun.

Cloud Model In the 1920’s

scientists found electrons do NOT orbit around the nucleus like planets, instead they can be anywhere in a designated “cloud” region, called an energy level.

Modern Atomic Model

In 1932, Chadwick discovered the neutron, a neutral particle within the nucleus.

Modern model = at the center of the atom is a tiny nucleus containing protons and neutrons. Surrounding the nucleus is a cloudlike region of moving electrons.

Scientist/Model QUIZ Match the atomic structure/model with

the scientist: Dalton, Rutherford, Thompson, Bohr, Chadwick, Democritus

1. Orbiting planet model2. Gold foil experiment3. Nucleus4. Electron5. Proton6. Neutron7. Energy level8. “Atom”

Parts of the AtomNucleus: atom’s central core, made up

of protons and neutrons, is positive in charge

Proton (p+): subatomic particle that has positive charge, has some mass

Neutron (n): subatomic particle that has no charge or is neutral, same mass as proton

Electron (e-): subatomic particle that has a negative charge, relatively no mass

Comparison Chart

Atoms have no charge overall since protons balance out electrons.

Particle Symbol Charge Mass Location

Proton p+ +1 ~ 1amu Nucleus

Neutron n 0 ~ 1amu Nucleus

Electron e- -1 ~ 0amu Outside nucleus

Atomic Structure Atomic Number: number of protons in

the nucleus of an atom Atomic # = # of p+

Determines the identity of the element Periodic table is organized by atomic

number Ex: What is the atomic number of…

He ______ C ______ N ______ O ______

Summary:

Create a BRACE MAP to illustrate the structure of the ATOM Use the following words:electrons atom electron cloudNeutrons nucleus protons

Chapter 4 Section 2 Notes

Organizing The Elements11-2-12Page #

Meet the Elements Song

I. Mendeleev’s Periodic Table By 1869, 63 elements had been

discovered. Mendeleev found a way to organize them.

He arranged them by atomic mass, the average mass of all the isotopes of an element.

He noticed a pattern of properties in the table and was able to predict where future elements would occur!

II.Modern Periodic Table

The modern periodic table is organized by the number of protons or atomic number.

The properties of an element can be predicted from its location on the periodic table.

According to periodic law, when elements are arranged this way, similarities in their properties will occur in a regular pattern.

III. Finding Your Way Around The Periodic Table:

Classes of Elements: Elements are classified as metals, semimetals,

or nonmetals. The zigzag line on the periodic table separates

the metals from the nonmetals

III. Finding Your Way Around The Periodic Table:

Periods: The horizontal rows. The properties of elements in a row follow a

repeating pattern as you move across each period.

III. Finding Your Way Around The Periodic Table:

Groups (Families): The vertical columns (top to bottom). Elements in the same group have similar

characteristics.

III. Finding Your Way Around The Periodic Table:

Reading the Data: Each square in the table gives: atomic number chemical symbol element name atomic mass

Chemical Symbol = representation of an element usually consisting of 1 or 2 letters

Meet The Elements…

Meet the Elements Song

State of Matter

Periodic Table displays the state of matter element is in at room temperature

Solids: Most common on table Liquids: Only 2-5 total on table Gases: in upper, right hand corner

Classification Metals: elements that are shiny,

bendable, conduct heat and electricity well. Most common, take up left and middle of

table Nonmetals: elements that conduct heat

and electricity poorly. Located in upper, right corner of table

Metalloids: located in between metals and nonmetals, on “staircase” Semiconductors: element that conducts

fairly well

Chapter 4 section 3 Notes

November 6th

Notebook page 81

Properties of Metals The Reactivity of metals tends to decrease as you

move from left to right across the periodic table Physical Properties:

Luster (shiny) Malleability = material can be hammered or

rolled into sheets/shapes Ductility = material can be pulled out into wire Thermal conductivity = ability to transfer heat Electric conductivity = ability to transfer

electric current

Properties of Metals Chemical Properties:

Reactivity = ease and speed substance reacts with other substances Decreases as you move from

left to right on table! Corrosion = gradual wearing away

of a metal due to chemical reaction

Alkali Metals Group 1: Alkali Metals

React w/ other elements by losing 1 electron

Super reactive; always found in compounds, never alone in nature

Soft, shiny Ex: sodium, lithium,

potassium

Group 1: Alkali Metals

Turn to page 76 in your notebook and label your periodic table.

Alkaline Earth Metals Group 2: Alkaline Earth Metals

Hard, gray-white, good conductor of electricity, fairly reactive

Form compounds found in limestone and in human body

React by losing 2 electrons Ex: magnesium, calcium,

barium

Group 2: Alkaline Earth Metals

Turn to page 76 in your notebook and label your periodic table.

Transition Metals: Groups 3-12, Group that contains the

MOST elements Conduct heat and

electricity Hard, shiny, colorful Ex: copper, iron,

mercury, silver, gold, nickel

Transition Metals

Groups 13-15, some are metals (Aluminum, Gallium, Indium, Thallium, tin, lead, bismuth)

Never found uncombined in nature

Metals in Mixed groups

Metals in Mixed Groups

Atomic numbers 57-71, rare earth metals, used to make

alloys

Lanthanides

Atomic numbers 89-103 radioactive, some are synthetic

(man-made), unstable (Uranium)

Actinides

Synthetic Elements Synthetic elements are made by scientists

by forcing nuclear particles to crash into one another. The nuclei break apart quickly so this makes it

difficult to determine properties of newly discovered elements

Elements numbered 92 and greater Particle accelerator = moves atomic nuclei

at high speeds causing them to crash into each other, sometimes combine into single nuclei

Chapter 4 Section 4

November 7, 2012Notebook Page 83

Nonmetals Physical Properties:

Dull Brittle Poor conductor

of heat and electricity

Basically the OPPOSITE of metals!

Chemical Properties: Gain or share

electrons Metals and

nonmetals often react together

Nonmetals Located on the right side of table Abundant on Earth

Oxygen and Nitrogen make-up 99% of atmosphere

Carbon is in more compounds than any other elements combined!

Group 17: Halogens Very reactive Dangerous to humans Ex: Fluorine, Chlorine,

Bromine, Iodine, Astatine Group 18: Noble/Inert

gases: Unreactive Do not usually form

compounds Ex: Helium, Neon, Argon,

Krypton…

Semimetals/Metalloids Contains only 8 elements,

found along boundary between metals and nonmetals Have properties of both metals and nonmetals Ex: Boron, Silicon, Arsenic… Are semiconductors: conduct heat and

electricity under certain conditions Silicon used in computer chips to speed up

conduction

Radioactive Elements

4-5

Radioactivity

Radioactive decay = atomic nuclei of unstable isotopes release fast-moving particles and energy.

Radioactivity = element which spontaneously emits radiation

First discovered by Becquerel in 1896 with uranium.

Types of Radioactive Decay Radioactive decay can produce 3 types of

radiation: Alpha Decay: an alpha particle consists of

2 protons and 2 neutrons and is positively charged. Can be stopped by a thin layer

Beta Decay: a neutron is converted into a beta particle, a fast-moving electron Can be stopped by thick material

Gama Decay: high-energy waves Can only be stopped by thick

concrete or lead

As uranium decays it becomes multiple elements releasing multiple types of radiation!

Uses of Radioactive Isotopes Radioactive isotopes can include the

tracing steps of a chemical reactions, industrial processes, and diagnosing and treating disease.