Atomic
Structure
Science 10
Atom Models
 Models
have
changed and
become more
detailed over time
 Each model has
allowed for new
hypotheses to be
made and predictions
to be tested
Parts of an Atom
 Atoms



are made up of subatomic particles
Protons (p+)
Neutrons (n)
Electrons (e-)
 The
atoms for each element have a different
number of subatomic particles
 Atoms are neutral

They have no charge
Inside the Atom
Relative Size in an Atom
Atomic Number
 Atoms
from different elements have
different number of protons (p+)
 Atomic number = number of protons
 Because atoms are neutral

Number of protons=number of electrons (e-)
Mass Number
 Mass
number = protons (p+) + neutrons (n)
 To solve for number of neutrons

Neutrons = mass number - protons
Atomic number = 2
Mass number = 4
Helium Atom
Number of protons =
Number of electrons =
Number of neutrons =
Mass Number
 Mass
number = protons (p+) + neutrons (n)
 To solve for number of neutrons

Neutrons = mass number - protons
Atomic number = 2
Mass number = 4
Helium Atom
Number of protons = 2
Number of electrons = 2
Number of neutrons = 2
Isotopes
 Isotope
– atoms of the same element that
have different number of neutrons
 Have the same atomic number
 Have different mass number

Different number of neutrons
Isotopes
 Have


How they react
This is based on their valence electrons
 Have

the same chemical properties
different physical properties
Appearance, density, diffusion behaviour
Common Isotopes
3 Isotopes of Hydrogen: 1H1 2H1 3H1
2 Isotopes of Carbon: 12C6 14C6
2 Isotopes of Chlorine: 35Cl17 37Cl17
Electron Configuration
 The
number of electrons that each
energy level (orbital, shell) can hold
 Atoms
have 7 energy levels which each
have a maximum number of electrons



Level 1 – Holds 2 electrons
Level 2 – Holds 8 electrons
Level 3 – Holds 8 electrons
 Electrons
always fill the first energy level
before filling the second, etc.
Electron Configuration
Electron Configuration
 Electron
configurations are written with
the number of electrons in each energy
level followed by a comma
 Sodium: 23Na11 has 11 electrons: 2, 8, 1
 Beryllium: 9Na4 has 4 electrons: 2, 2
Fill in the following table by using your periodic table
12C
Si
He
P
Ne
12C
F
Al
O
6
6
Understanding Checkpoint
 Read
and hi-light textbook pg.
 Read handout on radioisotopes
 Worksheets
 Quiz in 2 classes
Next Up
 Quiz
 Ions
 Valence
electrons
 Video
 Periodic
Table Lesson