Atoms, Isotopes and Ions…Oh My!SOL Covered:

PS.3, PS.4a & bCH.2 a, b, c, g & i

Aron Fristoeafristoe@msinnovation.info

Objectives

• Review the history of Atomic Theory

• Emphasize the importance of the Quantum Model

• Build atomic models with appropriate atomic mass and electron configuration

• Build models to represent ionic and covalent bonding

A Brief History of the Atom

What is Matter Made of? Aristotle vs. Democritus

(Around 2400 years ago)

What is Matter Made of? Aristotle vs. Democritus

(Around 2400 years ago)

John Dalton

Dalton’s Theory Based on Experimentation!

• chemical elements are made of atoms. • the atoms of an element are identical in

their masses• atoms of different elements have different

masses • atoms only combine in small, whole

number ratios• atoms can be neither created nor

destroyed

Dalton’s Atomic Model

J.J. Thomson

Ernest Rutherford

BOTTOM LINE- The nucleus is dense and positive and the atom is mostly empty space!

Atoms are Mostly Empty Space

Imagine a raisin on home plate to represent the nucleus

The first electron would be represented by the outfield wall.

Niels Bohr

• Rutherford quickly realized that his model would cause the electrons to be pulled into the nucleus and destroy the atom

• In 1913, Niels Bohr hypothesized that the electrons were in fixed energy levels at a set distance from the nucleus and that each energy level could hold a certain number of electrons.

Bohr Model Continued

• Energy levels are sometimes called “shells”

• Each shell can hold a fixed number of electrons

• Electrons are particles but the position and velocity can not be determined at the same time– Heisenberg

Uncertainty Principal

The Quantum ModelThe “Modern” Model

• In the early 1920’s, and Irwin Schrödinger theorized that the electrons behaved like particles and waves. His model kept electrons energy levels and the energy levels were broken into sub-levels.

• The energy levels aren’t traditional “orbital's” but areas where an electron has a high probability of being found.

Quantum Orbital's Have Interesting Shapes

The Quantum Model is also known as The Electron Cloud

Even though the Quantum/Electron Cloud Model is the most accurate, the Bohr Model

is still used to help students understand atomic structure since it’s simplistic.

Correct- Quantum Model/Electron Cloud

Bohr’s model while not completely accurate, helps students understand energy levels and placement of electrons.

So what’s the difference between protons, neutrons and electrons?

Let’s Build Some Models!

Hydrogen-1

Make an atom for…

Hydrogen-2

Make an atom for…

So what’s the difference between…

and

has 1 more neutron

and are _______ of HydrogenISOTOPES

Helium-4

Make an atom for…

Make an atom for…

Make an atom for…

Make an atom for…

Nitrogen-17

Make an atom for…

Let’s Take a Break and Play a Game

• Slowly move around the designated area looking down

• When you bump into someone, share your number– The lower number will give 1 bean to the

higher number

• Continue until I call stop

Now let’s make some Ions…

Make an atom for…

2-

Atoms with a NEGATIVE net charge are called ANIONS

2-

Make an atom for…

1+

Atoms with a POSITVE net charge are called CATIONS

Ionic BondingChemical Bonds Between Metals and Nonmetals

Sodium and Chlorine

Na11 electrons

Cl17 electrons

Sodium and Chlorine

Na1+

10 electrons

Cl1-

18 electrons

Electron from Na

8 electrons in each outer energy level

Sodium chloride

NaCl

Opposites attract!

Calcium and Chlorine

Ca ClCalcium has 2 electrons in it’s outer energy level

Calcium and Chlorine

Ca2+ 2Cl1-

Calcium donates one electron to 2 Chlorine atoms

Calcium chloride

CaCl2

Covalent BondingChemical bonds between two or more nonmetals

Hydrogen and Oxygen

2H O

Water

H2O

Water

Each Hydrogen atom has two electrons- the maximum number in the first (and only for Hydrogen) energy level

Water

The Chlorine atom has 8 electrons in the second energy level which is the maximum number of electrons that the second energy level can hold.

Ammonia (nitrogen trihydride)NH3

Nitrogen atom

3 Hydrogen atoms

Ammonia (nitrogen trihydride)NH3

Ammonia (nitrogen trihydride)NH3

Each Hydrogen has 2 electrons which is the maximum it can hold in it’s outer energy level.

Ammonia (nitrogen trihydride)NH3

Nitrogen has 8 electrons in it’s outer energy level which is the maximum number of electrons the second energy level can hold.

Methane (carbon tetrahydride)CH4 For chemistry, you can use this

to talk about sp hybridization (specifically sp3)