ATOMS

• Basic building blocks of matter.– Atoms make up everything (that has mass

and takes up space).

Atomic Structure

• Protons – positively charged particles inside the nucleus.

• Neutrons – neutral particles inside the nucleus that have No charge.

• Electrons – negatively charged particles in atoms found around the nucleus.

A = P = E M – A = N

•Atomic # = Protons = Electrons

•Mass – Atomic # = Neutrons

Atomic Particle Size

Atomic Mass Unit - amu

• Unit of measurement for the mass of subatomic particles.– 1 amu = 1.7 X 10 -24 They are TINY!!!

• .000000000000000000000017 grams

– Proton = 1 amu– Neutrons = 1 amu– Electrons = almost zero (TINIEST particle with

the least mass)– Most mass is in the nucleus with protons and

neutrons– Otherwise atoms are mostly EMPTY SPACE

Atomic Number

• The number of protons inside the nucleus of the atom.

• Determines the element.

• Atoms have no charge because the # of protons (+ charge) is = to the # of electrons (- charge).

Mass Number/Atomic

Mass• The total number of protons and

neutrons in an atoms nucleus.

• Protons + Neutrons = Mass Number

• Notice how massive the nucleus is compared to the rest of the atom

Atomic Mass

• The weighted average of the masses of all the naturally occurring isotopes of an element.

• Average of Protons + Neutrons of all an elements Isotopes = Atomic Mass

Electron Cloud

• Area around the nucleus where electrons are arranged.

• Energy Levels – Levels within the electron cloud that hold a specific # of electrons.

– 1st level - 2 electrons– 2nd level - up to 8 electrons– 3rd level – up to 8 or 18

Valence Electrons

• The electrons in the outermost energy level (electron cloud).

• What element is this?

• How many valence electrons does it have?

ELEMENTS

• All the atoms that make up our universe• Identified by the atomic # (# of protons)

3 Main Groups on the Periodic Table

Metals

• Make up most of the elements• All solid except Mercury• Has luster (shiny)• Good conductors of heat and

electricity• Malleable – made into different

shapes• Ductile – made into wires

Metals

Nonmetals

• Usually gases or brittle solids• Poor conductors of heat and

electricity• Right side of the periodic table• Only 17 nonmetals

Metalloids

• Called Semi-metals• Share properties of both metals and

nonmetals

Groups/Families

• Columns of the periodic table

• Each element has the same # of valence electrons

• The elements share similar chemical and physical properties.

• They are each part of the same “family”

Periods

• 7 rows on the periodic table

• Consist of elements with the same number of electron levels.

Alkali Metals

• Group #1• All metals• 1 Valence Electron• Very reactive• Most reactive – the

only need to lose 1 valence electron in chemical bonds

Alkaline-Earth Metals

• Group #2• All Metals• 2 Valence

Electrons• Very reactive but

less than group #1.• Only have to lose 2

valence electrons in chemical bonds

Valence Electrons

• Group 1 – all elements have 1 valence electron

• Group 2 – all elements have 2 valence electrons

Transition Metals

• Groups # 3-12

• All metals

• 1 or 2 valence electrons

• Less reactive than group #2

• Also contains lanthanide and actinide series

Groups # 13-16

• Elements change from metals to nonmetals and include the metalloids.

• Atoms have 10 fewer valence electrons than the group #.

• Boron Group #13 - 3 valence electrons• Carbon Group #14 - 4 valence electrons• Nitrogen Group #15 - 5 valence electrons• Oxygen Group #16 - 6 valence electrons

Halogens

• Group 17• All nonmetals• 7 valence electrons• Very reactive

– Only need to gain 1 more electron for a total of 8!

Noble Gases/Inert Gases

• Group # 18• All nonmetals• 8 valence electrons

- except helium only has 2.

• Unreactive– Have a full outer

electron level– 2 on the 1st level– 8 on the 2nd level

Hydrogen stands alone

1 valence electronVery reactiveColorless, odorless

gas at room temperature.

Low densityReacts explosively

with Oxygen