Atomic StructureScience 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 = 2Mass number = 4

Number of protons =Number of electrons = Number of neutrons =

Helium Atom

Mass Number

Mass number = protons (p+) + neutrons (n)

To solve for number of neutrons Neutrons = mass number - protons

Atomic number = 2Mass number = 4

Number of protons = 2Number of electrons = 2Number of neutrons = 2

Helium Atom

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 the same chemical properties How they react This is based on their valence electrons

Have different physical properties Appearance, density, diffusion behaviour

Common Isotopes3 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,

212C6 Si He

P Ne 12C6

F Al O

Fill in the following table by using your periodic table

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