Compounds
Compounds
• Substance formed by the chemical
combination of two or more elements in
definite proportions
• Example: WATER!
• Water is NOT an element! Made up of 2
elements!!
CaCO3
• Calcium carbonate
– How many atoms of calcium?
– How many atoms of carbon?
– How many atoms of oxygen?
LET’S CHECK YOUR BELLRINGER
ALMOST ALL ELEMENTS EXIST IN A
COMPOUND FORM.
MOLECULE
• Structure that results when atoms join
together.
• Smallest unit of most compounds.
Why do compounds form?
• Stability
VALENCE ELECTRONS = ELECTRONS
IN THE OUTERMOST RING
PERIODIC TABLE IS ORGANIZED
ACCORDING TO REACTIVITY…OR THE #
OF VALENCE ELECTRONS
IN ORDER TO BE STABLE, THE
OUTERMOST ELECTRON RING MUST BE
COMPLETELY FILLED.
ATOMS IN COMPOUNDS ARE HELD
TOGETHER BY BONDS.
LET’S MAKE ONE OF THE MOST
PREVALENT COMPOUNDS IN YOUR
BODY!
Bond Types
• There are two types of bonds:
– Ionic
– Covalent
Remember…
• Why do atoms bond in the first place?
• What is the key subatomic particle involved in
bonding?
What is going on in each picture?
Which picture would best match IONIC BONDS? Which
picture would best match COVALENT BONDS?
A
B
Ionic Bonds
• Formed when one or more electrons are
transferred from one atom to another. (ions)
• The resulting oppositely charged ions are
attracted to each other – forming the bond
Covalent Bonds
• Forms when electrons are shared between
atoms.
Covalent Bonds
• Most commonly found bond in compounds
that make up living things.