Basic C hemistry Lecture I

Basic Earth Chemistry

Physical Properties Density Color Hardness Melting Point Boiling Point Ability to conduct electricity

Density Used to describe matter. Density is the measure of the mass of an object divided by its volume. An object that is more dense than water will sink, whereas one that’s less dense will float.

Density = Mass/Volume D=m/v A small cube has a volume of 2 cubic centimeters and its mass is 8 grams. What is the cubes density? ______grams per cubic centimeter

Chemical Properties Example: Water Made up of 2 hydrogen molecules and one oxygen molecule. Has specific melting, boiling, and freezing point.

A chemical property of Iron is that it interacts with oxygen to form rust

A chemical property of helium is that it does not usually interact with other substances,

Structure of an Atom

Protons: positively charged subatomic particles (+) Neutrons: neutrally charged subatomic particles (N) Electrons: Negatively charged subatomic particles.

IONS Electrically charged (non-neutral) atoms are called ions. This happens when atoms gain or lose electrons.

Always have in notebook!!!!!!!

Element: Substance that cannot be broken down into simpler form by ordinary chemical means.

3 Physical Forms of Matter Solids Liquids Gases

Solids Molecules are in a fixed position Result in definite size and shape.

Liquids Molecules are close together and move freely. Takes the shape of its container.

Gases Molecules are freely moving and independent. Completely fills its container.

Plasma Most of the matter in the universe is in the plasma state. Matter in this state is composed of ions and electrons. Stars are composed of matter found in the plasma state.

Chemical Bonds 1. Ionic Bonds: Interaction of electrons from the outermost energy level of two or more atoms. Example: NaCl

Chemical Bonds 2. Sharing of Electrons Example: Water

Which bonds are stronger? Covalent bonds are far weaker than the powerful attraction in ionic bonds

Earth/Chemistry Link Alloys: solution of two or more metals Brass: A solution of Copper and Zinc Bronze: A solution of Copper and Tin

Bronze Brass

Density Problem The volume of a mineral is 9 cubic centimeters. Its mass is 81 grams. What is the density of the mineral? ______ grams per cubic cm.