Elements
K
element
The smallest form of matter. It cannot be broken down into othr types of substances.
What does the electron cloud look like?
What is a physical change?
A change that can return to its previous form: ice, water, ice, water.
H20
Hydrogen2 + Oxygen
Nitrogen
N
compounds
When two or more DIFFERENT elements combine.
When is an element unstable?
When it has an excess of neutrons or electrons.
What is a chemical change?
A change that can't be put back to its previous form:
wood, ash, wood, ash
H2O2
Hydrogen2 + Oxygen2
Chloride
Cl
Covalent bond
The sharing of electrons between atoms.
Why do elements react with each other?
They want to become stable and happy. They are happy with a full, outer shell.
What is the difference between a physical and chemical change?
A chemical change can never go back!
NaCl
Sodium + Chlorine
Carbon
C
molecules
When two or more elements combine
How are electrons involved in elements reacting with each other?
The valence electrons bond one atom to another.
What is the Law of Conservation of Matter?
The same amount of matter exists before and after the change. None is created or destroyed.
2HNO3
2 hydrogen
2 nitrogen
6 oxygen
10 total
Sodium
Na
An atom or molecule with one or more plus or minus charges.
What molecules make up air?
N
O
CO2
Who discovered the atom?
John Dalton
(NH4)3PO4
4 N
12 H
1
P
4 O