1. ATOMIC STRUCTURE
Democritus - Greek philosopher coined the term “atom” - unable to be divided
Suggested atoms make up matter in 4th century BC
He was unable to provide evidence that atoms really existed.

2. 1808 - John Dalton All elements are composed of tiny particles
called atoms. Atoms can’t be divided.
2. Atoms of the same element are identical.
3. Atoms can join together to form
compounds.
Chemical reactions occur when atoms
are separated from each other, joined, or
rearranged in different combinations.

3. Composition of an Atom
Nucleus - center of the atom
protons - positive particles
neutrons - no charge
electrons - negative particles
- move around the
nucleus

5. SUBATOMIC PARTICLES Particle Charge Mass Location Proton + 1 amu
nucleus
Neutron
Electron -
~ 1/2000
amu
outside

7. Bohr Model
Electrons orbit nucleus like the
planets orbit the sun
Electrons path defines its energy
level
Electrons gain energy as they
move farther from the nucleus

8. Wave/Quantum Mechanical Model
Electrons behave like waves on a
vibrating string (de Brolie).
We cannot determine their exact location,
only their atomic orbital, the region
where they are likely to be found.
Energy levels of electrons are labeled by
principle quantum numbers (n).

9. Wave/Quantum Mechanical Model
For each principle quantum number greater than one, there are energy sublevels.
Each energy sublevel corresponds to one or more orbitals of different shapes. The orbitals describe where an electron is likey to be found.

10. Wave/Quantum Mechanical Model

11. Wave/Quantum Mechanical Model
Principle # of Type of Maximum #
Energy Level Sublevels Sublevel of electrons
n = s (1 orbital) 2
n = s (1 orbital) 2
2p (3 orbitals) 6 = 8
n = s (1 orbital) 2
3p (3 orbitals) 6
3d (5 orbitals) 10 = 18

12. Wave/Quantum Mechanical Model
Valence electrons - electrons in the
outermost energy level

13. QUIZ-1
1. List 4 points of Dalton’s atomic theory.
2. What is the charge of an electron?
3. Why does the atom have no electrical charge?
4. What subatomic particles make up the nucleus of the atom?
5. Whose atomic model is known as the planetary model?

14. 6. Whose atomic model is described as
the plum pudding model?
7. Explain the modern wave/quantum
mechanical atomic model.
8. Draw a model of the atom with
6 protons and 4 neutrons.
9. How many valence electrons does the
atom you drew in question 8 have?
10. Energy levels of electrons are labeled
by _____________.

15. THE PERIODIC TABLE
Periodic Law - When elements are put in order of their atomic number, similarities in their properties occur in
a regular pattern.
Elements are arranged in order of increasing atomic number.

17. Periods – there are 7 horizontal rows
- patterns can be seen from
left to right across the period
- Elements become less metallic
Each row corresponds to a principle
energy level.
Group or family - vertical columns
- elements in the same group have
similar chemical and physical
properties

18. Ion - charged atom
Periodic Table can determine the charge, ex. Group 1A elements charge is (1+), Group 7A elements charge is (1-)
Positive ions - lose electrons
Negative ions - gain electrons

19. Atomic number - number of protons
- top of square
Mass number - protons + neutrons
- bottom of square
Isotope- atoms of same element,
have same # of protons,
different # of neutrons

20. Average atomic mass - average
mass found for that element
in nature
amu (atomic mass unit)- unit of
mass for atoms

21. Classifying Atoms
Metals - on left of the zigzag line
- shiny, good conductors of
heat and electricity
- malleable - can be hammered
into a thin sheet
- ductile - made into thin wire

22. Nonmetals-right of the zigzag line
- dull and brittle
- poor conductors
Semiconductors (metalloids)
- on either side of the zigzag line
- characteristics of both metals
and nonmetals

24. METALS
Alkali metals (group 1) - most reactive
ex. Na (NaCl - salt)
Alkaline-earth metals (group 2) - less
reactive than alkali metals, but
still reactive
ex. Calcium compounds form hard
shells of many animals, limestone,
bones and teeth

25. Transition metals - less reactive than
other metals
-can be found alone (uncombined)
in nature, ex. Gold
-used to make jewelry (Ag, Au)
- Cu - wiring, plumbing
- Hg - thermometers
(only metal that is liquid
at room temperature)

26. NONMETALS
Carbon - found in all living things
- in its pure state is usually
found as graphite (pencil
“lead”
Oxygen - vital to most living things
Nitrogen - fertilizer
- 79% of air

27. Halogens (group 7A) - salt formers
Chlorine - in bleach, a disinfectant
Iodine - helps thyroid gland
function properly
Fluorine - in water, toothpaste
(helps prevent tooth decay)

28. NOBLE GASES (group 8A)
-inert (don’t react)
-unreactive because their electron
shell is full
-ex. Neon - used in lights
Helium - balloons

29. SEMICONDUCTORS
Boron - added to steel to increase its
hardness and strength
Antimony - a fire retardant
Silicon - found in sand (SiO2)
- silicon chips (LED screens,
computers)

30. QUIZ-part 2
What are the horizontal rows in the periodic table called?
2. What are the columns in the periodic table called?
3. Define isotope.
What is the difference between atomic number and mass number?
5. State the periodic law.

31. QUIZ-part 2 continued
6. What is the group name of the most
active metals?
7. What is another name for metalloids?
8. Give 3 characteristics of metals.
9. Give 2 characteristics of nonmetals.
10. What is the name of the group 2 metals?
11. List 2 places where calcium is found.

32. 12. What does the word halogen mean?
13. What element makes up about 80%
of air?
14. What does the word inert mean?
15. List an example of a transition metal
and give a use of it.