8 - Unit 1, Section 1 - Day 2

Atoms and Elements: A Review

Unit 1, Section 1

Match

Match the following three subatomic particles to their descriptions.

• Proton

• Neutron

• Electron

Positive, In The Nucleus, Relatively Large

Neutral, In The Nucleus, Relatively Large

Negative, Orbiting The Nucleus, Relatively Small

• Positive, In The Nucleus, Relatively Large

• Neutral, In The Nucleus, Relatively Large

• Negative, Orbiting The Nucleus, Relatively Small

We've learned that:

• Protons determine the element of an atom

• Neutrons determine how stable an atom is

But what about electrons?

What About Electrons?

Open Ended

What purpose do you think electrons have in an atom?

• For every proton in the nucleus, there is an electron orbiting around it

• For every positive charge, there is a negative charge, so the total charge on an atom is zero

• For atoms, the atomic number is also equal to the number of electrons

Electrons balance protons

Electrons do not orbit the nucleus in random places

• Electrons orbit the nucleus in energy levels that are different distances from the nucleus

• Every level can hold a certain number of electrons

energy Levels

There are two types of electrons:

• Valence electrons are the electrons in the outermost energy level

• Core electrons are the rest, between the valence electrons and the nucleus

Types of Electrons

• Valence electrons allow atoms to bond to other atoms

• This forms chemical compounds

What Do Valence Electrons Do?

The number of valence electrons determine:

• What kinds of chemical bonds can form

• How many chemical bonds can form

So, how can you determine how many valence electrons an atom has?

How Many Valence Electrons?

Using The PEriodic Table!

The group (column) of the periodic table equals the number of valence electrons for every element in that group!

Open Ended

You can't use the rule in the previous slide to determine the valence electrons in an atom for some groups on the periodic table. Which are those groups?

Multiple Choice

How many valence electrons are in an atom of sulfur (S)?

• 3

• 6

• 16

• Can't Be Determined

Multiple Choice

How many valence electrons are in an atom of astatine (At)?

• 6

• 7

• 85

• Can't Be Determined

Multiple Choice

How many valence electrons are in an atom of ruthenium (Ru)?

• 5

• 8

• 44

• Can't Be Determined