1. I. Structure of the Atom Dalton’s Atomic Theory Subatomic Particles
Ch. 4 - Atomic Structure
I. Structure of the Atom
Dalton’s Atomic Theory
Subatomic Particles

2. A. Dalton’s Atomic Theory
Every element is made of tiny, unique, particles called atoms that cannot be subdivided.
Atoms of the same element are exactly alike.
Atoms of different elements can join to form molecules.

3. B. Subatomic Particles in a neutral atom Atomic Number
NUCLEUS
ELECTRONS
in a neutral atom
PROTONS
NEUTRONS
NEGATIVE CHARGE
POSITIVE CHARGE
NEUTRAL CHARGE
Most of the atom’s mass.
Atomic Number
equals the # of...

4. Atomic Number = # of Protons & Electrons Atomic Mass = # of Protons
B. Subatomic Particles
Element Symbol 10
Atomic Number = # of Protons & Electrons Ne
Element Name
Neon
Atomic Mass = # of Protons +
# of Neutrons
20.179

5. B. Subatomic Particles
Atoms have no overall charge because the protons (+) cancel out the electrons (-).
Neon
10 protons = +10
10 neutrons = 0
10 electrons = -10
total charge 0

6. II. Electron Cloud Model Orbital Energy Levels Bohr Model Diagrams
Ch. 4 - Atomic Structure
II. Electron Cloud Model
Orbital
Energy Levels
Bohr Model Diagrams

7. B. Energy Levels Electrons can only exist at certain energy levels.
Low energy levels are close to the nucleus.
Each energy level (n) can hold a certain number of electrons.

8. A. Orbital
Region where there is 90% probability of finding an electron.
Can’t pinpoint the location of an electron.
Density of dots represents the probability.

9. C. Bohr Model Diagrams
Simplified energy levels using Bohr’s idea of circular orbits.
Can replace with: 3p 4n
Lithium
Atomic #: 3
Mass:
# of p: 3
# of e: 3
# of n: 4 e- e- p n
Maximum e-
Level 1 2e-
Level 2 8e-
Level 3 18e-
Level 4 32e- e-

10. C. Bohr Model Activity Choose a number between 1 & 18.
Find your element by the atomic number you picked.
Draw a Bohr Model diagram for your element on your marker board.
Round off the atomic mass listed on the table and subtract the atomic # to find the # of neutrons.
Abbreviate the # of ‘p’ and ‘n’ in the nucleus.
Have a partner check your drawing.
Repeat with a new element.

11. III. Masses of Atoms Atomic Mass Mass Number Isotopes
Ch. 4 - Atomic Structure
III. Masses of Atoms
Atomic Mass
Mass Number
Isotopes

12. A. Atomic Mass atomic mass unit (amu) – unit of measurement
Average atomic mass – the average mass of all the isotopes of the atom.
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13. B. Mass Number
Sum of the protons and neutrons in the nucleus of an atom.
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Always a whole number.
# of neutrons = mass # - atomic #

14. C. Isotopes Mass # Atomic #
Atoms of the same element with different numbers of neutrons.
Isotope symbol:
Mass #
Atomic #
“Carbon-12”

15. C. Isotopes
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