Intro to Atom/Periodic Table

Atomic Mass

# of protons + # of neutrons

How many total electrons does an aluminum atom have?

13

How many electron shells does carbon (C) have?

2

How many electrons can fit in the first shell?

2

How many valence electrons does aluminum have?

3

How many electron shells does potassium have?

4

How many valence electrons does carbon (C) have?

4

How many valence electrons does chlorine (Cl) have?

7

How many electrons can fit in the second shell?

8

How many valence electrons does neon have?

8

Solvent

A liquid substance capable of dissolving other substances

Solution

A mixture that forms when one substance dissolves another.

Compound

A pure substance made of two or more elements CHEMICALLY combined.

Element

A pure substance that cannot be broken down into other substances by chemical or physical means

Electron

A subatomic particle that has a negative charge and is found on the electron shells

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

Neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

Valence electron

An electron that is found in the outermost shell of an atom.

Atom

Basic unit of matter

How many valence electrons does helium have? (Careful!)

Helium has 2 valence electrons... (Not 8!) Helium only has 2 electrons total and they are all on the same shell. (Helium is the only exception to the rule about group number telling the number of valence electrons.)

Heterogenous mixture

Mixture which is not uniform throughout, the component substances can be visibly distinguished.

Homogenous mixture

Mixture which is uniform throughout, the substances are evenly mixed and cannot be visibly distinguished.

Solute

Substance being dissolved

Atomic Number

The number of protons in an atom

Molecule

Two or more atoms held together by covalent bonds.

Mixture

Two or more substances that are mixed together but not chemically combined

How many electron shells and valence electrons does magnesium have?

Valence electrons: 2 Electron shells: 3