Chemistry Vocabulary

Atomic Number
Number of protons within a the nucleus of a particular element.
Atom
Smallest most basic unit of matter.
Nucleus
Positively charged center part of an atom.

Contains Protons and Neutrons

Protons
Mass = 1
Charge = +1
Location = Nucleus
Neutron
Mass = 1
Charge = 0
Location = Nucleus
Electron
Mass = 0
Charge = -1
Location = Moving around the Nucleus
Atomic Mass
The number of protons + the number of neutrons
Charge
Relationship between protons and electrons

Charge = Protons – Electrons

John Dalton
(1803)
Central Ball
Hard Sphere
JJ Thomson
(1897)
Negative parts within the central ball.
Ernest Rutherford
(1906)
Postively charged central ball

Negative particles around the ball

Niels Bohr
(1913)
Electrons orbit the nucleus in defined paths.

Electrons found in different “energy levels”

Electron Cloud Model
(1926 – present)
Electrons are found with different “shells” or “clouds”

The do NOT follow defined paths as they move within their cloud.

Average Atomic Mass
The average mass of all an elmenets isotopes.

Located on the periodic table in a decimal form under the symbol(usually)

Malleable
Ability to be hammered or rolled into sheets
Ductile
Ability to be drawn into wire
Valence Electrons
Electrons found in the outer most shell

****Want to have 8****

(except the first shell takes 2)

Luster
Shiny
Isotope
Same element but with a different number of neutrons.

Example:
Carbone-12 or Carbon-13

(Name)dash(Mass)

Alkali Metals
Group 1

Li, Na, K, Rb, Cs, Fr

Alkaline Earth Metals
Group 2

Be, Mg, Ca, Sr, Ba, Ra

Transition Metals
Groups 3 – 12

Mn, Fe, Ni, Cu, W, Ag, Hg, Au…….

Metalloids
Touching the stair step

B, Si, Ge, As, Sb, Te, Po, At

Hallogens
Group 17

F, Cl, Br, I, At

Noble Gases
Group 18

He, Ne, Ar, Kr, Xe, Rn

Compound
The combination or bonding of 2 or more atoms.
How many valence electrons does Na have?
One
Ionic Bond
A chemical bond formed by the attraction between opposite charged ions.

Between a METAL and NON-METAL

Covalent Bond
Chemical bond formed between two or more atoms by sharing electrons.

Between a NON-METAL and NON-METAL

Nonpolar Molecule
A covelent bond with even sharing of electrons. The molecule is neutral with no charge.
Polar Molecule
A molecule with uneven sharing of electrons. This results in a slightly positive and/or negative charge.
What does (cr) stand for?
Crystal
What does (l) stand for?
Liquid
What does (s) stand for?
Solid
What does (g) stand for?
Gas
What does (aq) stand for?
Aqueous Solution
Physical Change
A change in a substances state of matter.

ie: changing from a solid to a liquid or a gas.

Chemical Change
A change in the chemical structure of a substance. Resulting in a chemical reaction.

**creating new substances here**

Law of Conservation of Mass
Matter cannot be created or destroyed.

The # of reactants in an equation MUST equal the # of products.

Exothermic
The release of energy and heat in an experiment.

Causes a rise in temperature due to the release of heat/energy.

Endothermic
Energy or heat is absorbed in this type of reaction. From the outside these reactions will feel cold.
Catalysts
Something that speeds up a chemical reaction.

It does NOT change it though, just makes it faster.

Inhibitors
This will stop or prevent a reaction from occuring.