1. Chapter 2 Section 1 The Nature of Matter

2. ATOMS… Atoms are the basic units of matter
Atoms are made up of three subatomic particles.
Protons- positively charged particles located in the nucleus of an atom.
Charge is +1
Neutrons- particles with no charge located in the nucleus.
Charge is 0
Mass similar to that of a proton.
Electrons- negatively charged particles that are in constant motion about the nucleus of an atom.
Charge is -1
Mass is very very very small. 1/1840 the mass of a proton.

3. Elements and Isotopes…
An Element is a pure substance that consists of only one type of atom.
118 known elements.
Of about 24 are found in living things.

4. Elements and Isotopes…
Isotopes are atoms of the same element that differ in the number of neutrons they contain.
MASS NUMBER = # of protons + # of neutrons
Carbon-12, Carbon-13, and Carbon-14

5. Chemical Compounds…
A chemical compound is a substance formed by a chemical combination of 2 or more elements.
Scientist use a shorthand method to write chemical compounds called a chemical formula.
EX.) H20, NaCl, K3PO4, 03

6. Chemical Bonds…
Chemical bonds are the attractive forces that hold elements together in a compound.
2 Main Types of Chemical Bonds…
Ionic Bonds- form when one or more electrons are transferred from one atom to another.
Ions are the positively or negatively charged particles involved in ionic bonds.
Covalent Bonds- form when electrons are shared between atoms.
Molecules- are the smallest unit of most compounds and also another name for a covalent compound.