Chem note 3 and 4

Atomic number

The number of protons

Does the proton number change

NO

Atomic mass

Average mass of the element, mass of only the protons and neutrons

Atomic mass is equal to

p+n, p is atomic number

Ionic charge

When the electrical charge changes

Gain and losing electrons

A atom becomes an ion when it gains lt loses electrons

Metals and electrons

Metals will lose electrons and become positive

Non metals and electrons

Non-metals will gain electrons and become negative ions

Period

Horizontal row on p.t

Group/family

A vertical column on the p.t. they share same physical and chemical properties

Names of the 5 major groups

Alkali metals, alkali earth metals, transition metals, halogen, noble gases.

Alkali metals

Group one, silver/Grey, malleable, ductile and can conduct(hydrogen is not included)

Alkali earth metals

Group 2, reactive but not as much as group 1

Transition metals

Group 3-12, metallic characteristics, can make different bonds

Halogens

Group 17, non-metal, solid liquid or gas, reactive as Group 2

Noble gases

Group 18, color,odor and tasteless, not reactive, becomes colorful when electricty passes

Atomic radius

The radius of the atoms, each new period is a new orbit for electrons

Reactivity

Means a 1 group is more reactive then another, 17 is more reactive then 16. Increases left to right.

Group number refers to

The number of valence electrons

Lewis structure rule

The number of electrons around it is only the valence electrons

Compound

A pure substances made out of 2 or more elements

2 types of compounds

Ionic, covalent

Ionic compound

Pure substances, atleast one metals and non metals, can conduct if dissolved, forms crystals, gains and loses electrons.

How do ionic compounds bond

Through negative and positive attraction

Covalent

Pure substance, only non metals, can’t conduct well, can be solid liquid and gas

How do covalent compounds bond

Through sharing electrons

Molecule

Two or more atoms joined by a chemical bond

Chemical formula

Tells the amount of atoms and the type ex:H20

Octet rule

Elements form compounds bc they unstable, so they go for 8 electrons to fill (or 2)

Subscript

Small number in the bottom right of an atom

Coefficient

Normal sized number before the atom ex 2H²0

Brackets

Everything in the bracket counts as one

Superscripts

Small number in the top right which shows how many electrons gained or lost.