# 05 Atomic Structure and Models 2020

```THE NATURE OF ATOMS
SECTION A.3 CHEMCOM NUCLEAR
• Non-ionizing
• ionizing
SECTION A.3 CHEMCOM NUCLEAR
• Alpha, beta, gamma
SECTION A.4 CHEMCOM-RUTHERFORD TO
BOHR
SECTION A.4 CHEMCOM-RUTHERFORD TO
BOHR
ATOMIC STRUCTURE
&amp; MODELS
WHAT MAKES UP AN ATOM?
 An atom is made up of
subatomic particles (protons,
neutrons, and electrons.) Protons
and neutrons are made up of
Quarks.
 An element is made up the same
type of atom.
What do you notice about the size of
each type of particle?
SUBATOMIC PARTICLES
Subatomic
Particles
Charge
Mass (amu)
Location
Proton
+1
1 (very large!)
nucleus
Neutron
0
1 (very large!)
nucleus
Electron
-1
.0005 (very very small!)
outside nucleus
What does an atom really look like?
WHAT HOLDS AN ATOM TOGETHER?
Because protons have a positive charge and electrons have
a negative charge, they are attracted to each other
because of the electromagnetic force
(opposite charges attract, like charges repel.)
PERIODIC LAW
• Periodic Law a law stating that the elements, when listed in order of their
atomic numbers, fall into recurring groups, so that elements with similar (chemical
and physical) properties occur at regular intervals.
Noble Gases
ATOMIC STRUCTURE &amp; THE PERIODIC
TABLE OF ELEMENTS
1. What does the
atomic number tell
you?
2. How do you find the
number of neutrons?
3. How do you find the
number of electrons?
BOHR MODEL
Bohr Model can be used to show neutral atoms,
isotopes and ions. It shows the basic subatomic
particles in the atom.
In the nucleus or center are circles. Each circle
represents a single neutron and proton. Protons
should have a plus or P written on them. Neutrons
should be blank or have an N.
In a circle around the nucleus are the electrons.
Electrons should have a minus sign or an e.
ELECTRONS
Electrons live in something called shells or energy levels.
Only so many can be in any certain shell.
The electrons in the outer most shell of any element are called
valence electrons.
BOHR MODEL PRACTICE
So let’s try it….
How to draw a Lithium atom
1-Look at the Periodic Table
2-Determine the number of protons
(Look @ the atomic number)
3-Then determine the number of
neutrons (Atomic mass – atomic number)
4-Then determine the number of
electrons (equal the number of protons in
a neutral atom)
3
Li
Lithium
7
BOHR MODEL LITHIUM
Protons = 3
3
-
Li
-
Electrons = Protons
2 in the 1st shell
Lithium
7
1 in the 2nd shell
ATOMIC MASS – ATOMIC NUMBER = NEUTRONS
7
3
=
4
-
ISOTOPES
An isotope is an atom that has the same number of protons, but a
different number of neutrons. Isotopes of the same element have
different mass numbers.. Elements have isotopes, the atomic mass
listed on the periodic table is a weighted average of all the naturally
occurring isotopes of an element.
How to represent an isotope:
Oxygen- 16 or 168O
THE OCTET RULE
•The octet rule states that atoms are the most stable
when their outermost electron shell is complete, or has
8 valence electrons in it.
•Atoms can achieve the octet rule either by gaining or
losing electrons (forming ions).
• Cations (Lose) = Positive Charge
• Anions (Gain) = Negative Charge
•
Created by G.Baker
www.thesciencequeen.net
VALENCE ELECTRONS AND IONS
• Since elements in the same group have the same number
of valence electrons, they also form the same ions.
POTASSIUM – BOHR MODEL
K
-
K+1
-
-
-
-
-
Ion
-
-
-
-
-
-
-
Neutral
Atom
-
-
-
-
-
-
-
-
1 electron in
outermost shell
Protons =
Electrons
-
-
-
-
-
-
• 8 electrons in
outermost shell
Created by G.Baker
www.thesciencequeen.net
Cation
Lost e-
CHLORINE-BOHR MODEL
Cl-1
Cl
-
-
-
-
-
-
-
-
-
-
-
Neutral
Atom
-
-
-
-
-
-
-
-
-
7 electrons in
outermost shell
Ion
-
-
-
-
-
Anion
Gained e-
-
-
• 8 electrons in
outermost shell
Created by G.Baker
www.thesciencequeen.net
```