The basic unit of all matter Small in size

Proton Neutron Electron

Proton and Neutron – NUCLEUS of the atom (center)

Electrons – found rapidly moving in energy levels (energy clouds)

Proton = Positive (+) Neutron = Neutral (0) Electron = Negative (e-)

Proton Neutron

Remember – the electrons are SOOOO LIGHT that they are not part of the mass (atomic weight)

There is an equal number of protons and electrons

If there are more protons – then the atom would have an overall POSITIVE charge

If there are more electrons – then the atom would have an overall NEGATIVE charge

Use the terms◦ Symbol◦ Atomic Weight (Mass)◦ Atomic Number

A Atomic Number

Symbol

Atomic Weight (mass)

Hydrogen Oxygen Nitrogen Carbon

There is also phosphorus and sulfur, but I only want you to focus on the four listed above.

The symbol for Krypton is

The mass number for Calcium is

The atomic number for Beryllium is

The symbol for Krypton is Kr

The mass number for Calcium is

The atomic number for Beryllium is 4

The number of molecules present

LARGE NUMBER written before the element symbol

Ex: 4CO2 There are 4 molecules of carbon dioxide

The number of atoms present

SMALL NUMBER written within the chemical formula

Ex: 4CO2 There are 8 atoms of oxygen Remember to distribute (4 x 2=8)

5C2H4 How many molecules are present? How many atoms of Carbon are present?

How many atoms of Hydrogen are present?

How many TOTAL atoms are present?

5C2H4 How many molecules are present? 5 How many atoms of Carbon are present?

10 (5x2 – remember to distribute) How many atoms of Hydrogen are present?

20 (5x4 – remember to distribute) How many TOTAL atoms are present?

30 (distribute and then add up) (5x2) = 10(5x4) = 20 10 + 20 = 30

A. Electrons B. Protons C. Neutrons D. Valence Electrons

A. Electrons B. Protons C. Neutrons D. Valence Electrons

Choice D is the most accurate answer here

A. GainedB. LostC. Shared

A. GainedB. LostC. Shared

In the outermost energy level of an atom

8 electrons!

8 – OCTET rule ◦ The outermost energy level will be complete

when it contains 8 electrons. ◦ Atoms will gain/lose/share electrons to reach this

stability!

****EXCEPTION****◦ Hydrogen and Helium follow the DUET RULE (can

only have 2 electrons in the outermost shell to be stable and unreactive)

A. CarbonB. NeonC. HeliumD. Magnesium

A. Carbon – 4 opportunities to bond (vacancies)B. NeonC. HeliumD. Magnesium – 6 opportunities to bond

(vancancies)

Neon is stable because it is a noble gas – already has 8 electrons

Helium is stable because it is also a noble gas – but follows duet rule so it has 2 electrons

Single Bond Double Bond Triple Bond

Single Bond◦ Atoms share 2 electrons (1 pair)

Double Bond ◦ Atoms share 4 electrons (2 pairs)

Triple Bond◦ Atoms share 6 electrons (3 pairs)

Types of Elements Number of atoms Location of atoms

Example – 1 Oxygen 2 Hydrogen

COVALENT BONDS

SHARING OF ATOMS!!

Phosphorus Hydrogen Nitrogen Oxygen

Phosphorus Hydrogen Nitrogen Oxygen

WATER

Changes or transforms one set of chemicals into another

CHANGES to the BONDS – breaking and reforming bonds

Reactants

Products

Reactants ◦ ENTER into a chemical reaction (before the arrow)

Products◦ PRODUCED by a chemical reaction (after the

arrow)

Reactants Products Coefficients Subscripts

C - Reactants D - Products A - Coefficients B – Subscripts

Reactants REACTto produce PRODUCTS

Matter cannot be created nor destroyed Arrangement of atoms is what is changed

Reactants must equal products

Na + Cl2 NaCl

ANSWER - NO

2Na + Cl2 2NaCl