• The Atom• Atomic Number • Mass Number• Isotopes• Elements• Periodic Table

Chapter 4

Atoms and Elements

What do all of these things have in common?

What Are Atoms?

• Atoms are the building blocks of matter.

• So what is “matter”?• Anything that has mass AND takes up

space.• Examples:

Atomic Theory

Atoms are the building blocks

of all matter, which included

elements

Democritus, JJ Thomson, E

Rutherford, N Bohr, Chadwick,

Shrodinger, current wave

theory

What Are Elements?

Pure substances made up of all the same type of atom (same # of: p+, n, e-)

The 4 most abundant elements on Earth are carbon, oxygen, hydrogen, and nitrogen (POINTER: COHN or NOCH)

112 elements known todayExamples: carbon

goldcalcium

What element do these things have in common?

Here’s a Hint…

IRON (Fe) Latin: ferrum

• Cheapest…• Most common…• Most useful…

• Used extensively for the making of STEEL

IRON (Fe) Latin: ferrum

It also carries oxygen in hemoglobin in red blood cells.

% Major Elements in the Body

O 65.0 % K 0.34C 18.0 S 0.26H 10.0 Na 0.14N 3.0 Cl 0.14Ca 1.4 Fe 0.004P 1.0 Zn 0.003 Mg 0.50

Symbols of Elements

Use 1 or 2 letter abbreviations Capitalize the first letter only

Examples:C carbon Co cobaltN nitrogen Ca calciumF fluorine Br bromine

O oxygen Mg magnesium

Symbols from Latin NamesElement Symbol Latin nameCopper Cu cuprumGold Au aurumLead Pb plumbumMercury Hg hydrargyrumPotassium K kaliumSilver Ag argentumSodium Na natriumTin Sn stannum

Take a guess what the correct symbol is for the element!

Select the correct symbol for each:A. Calcium

1) C 2) Ca 3) CAB. Sulfur

1) S 2) Sl 3) SuC. Iron

1) Ir 2) FE 3) Fe

Take a guess what the correct element is! Select the correct name for each:A. N

1) neon 2) nitrogen 3) nickelB. P

1) potassium2) phogiston3) phosphorus

C. Ag1) silver 2) agean3) gold

Periodic Table

The periodic table is an arrangement of the elements according to:

•The number of protons, neutrons, and electrons

•The way they look•The way they act

The Periodic Table

Shows the mass number and atomic

number

Gives the symbol of the element

mass number

23 Na or Na-23

atomic number 11

Groups of Elements

Vertical (up and down) columns

on the periodic table

Indicates the number of

electrons on the outer most shell

called valence electrons.

Periods on the Periodic Table

Horizontal (left to right) rows on the

Periodic Table.

Numbered 1-7

Indicates the number of

orbitals or shells the element

has.

Periods on the Periodic Table

123456

Using The Periodic Table

• In your notes, use your periodic tables to determine the following for the elements at the bottom.• The number of protons• The number of neutrons• The number of electrons on the outer most

shell (valence electrons)

•Calcium (Ca), Magnesium (Mg), Chlorine (Cl)

Subatomic Particles: Smaller Parts of an Atom

Particle Symbol Charge

Electron e- -1

Proton p+ +1

Neutron n 0

Location of Subatomic Particles

10-13 cm

electrons

protons

neutrons

10-8 cm

nucleus

Vocabulary

Neutral atoms = # of protons = # of electronsMass Number = # of p+ + # of nAtomic Number = # of protons Atomic Mass- the average mass of all of the isotopes.ion (unequal #’s of protons and electrons).

Cation-positive ionAnion – negative ion

Atomic Number

Counts the number of

?in an atom

protons

Ions• Cations

• Lost electrons (to other atoms)• When calculating number of e- subtract the

charge value from the original number of electrons.

• Anions• Gained electrons (from other atoms)• When calculating number of e- add the

charge value from the original number of electrons

Mass #

Counts the number of

? + ?in an atom

Protons and neutrons

Atomic Mass

Masses of theof

? isotopes

Subatomic Particles in Some Atoms

16 31 65 O P Zn

8 15 30

8 p+ 15 p+ 30 p+

8 n 16 n 35 n8 e- 15 e- 30 e-

Which number do you think is the atomic number? How do you know?

Drawing Bohr Diagrams

• Nucleus (p+ and no)• 1st energy level= up to 2 e-• 2nd energy level = up to 8e-• 3rd energy level = up to 18 e-• 4th energy level = 2 fill before 11-

18 in the 3rd energy level.

Bohr Diagrams

Electron Dot Diagram

• The symbol is the nucleus and inner energy levels

• Dots represent valence electrons• 8 total (2 on each side of symbol)• One each side, counterclockwise.

Electron dot diagrams

What Are Isotopes?

Atoms with the same number of protons,

but different numbers of neutrons.

Atoms of the same element (same atomic number) with different atomic masses.

Isotopes of Chlorine

35Cl 37Cl17 17

chlorine - 35 chlorine - 37

Learning Check

Naturally occurring carbon consists of three isotopes, C-12, C-13, and C-14. State the number of protons, neutrons, and electrons in each of these carbon atoms.

12C 13C 14C 6 6 6

#p _______ _______ _______

#n _______ _______ _______

#e _______ _______ _______

6

6

6

6

7

6

6

8

6

Calculating Average Atomic Mass

• Mass = (% x mass) + (% x mass)• 2 isotopes

• Mass = (% x mass) + (% x mass) + (% x mass)• 3 isotopes

• Make sure that % are in decimal form in your Calculator!!!!!