GeoFacts

•Only atmospheres that contain oxygen and water cause iron-bearing objects to rust. Therefore, the equipment that has been left on the Moon will never rust.•Mars is red because of abundant iron oxide, also known as rust, in the soil.

MATTER AND CHANGE

MATTER

Matter is anything that has mass and volume.Mass is the measure of the amount of material in

an object.Volume is the amount of space taken up by an

object.Element – substance that cannot be broken

down into simpler substances

ELEMENTS

Each element has a symbol as well as a name.Oxygen = OCarbon = C

A few element’s symbols are based on their Latin names.Gold = Au (aurum)Iron = Fe (ferrum)

Elements are made of tiny particles called atoms

ATOMIC STRUCTURE

Elements are made of tiny particles called atomsEach atom consists of three subatomic particles:

Particle Charge Location

Protons Positive Nucleus

Neutrons No charge Nucleus

Electrons Negative Around nucleus

THE NUCLEUS

In a normal state, atoms have an equal number of protons and electrons.Positive charges in the nucleus are attracted to the

negative charges that surround the nucleusThe number of protons and electrons determines

the element’s properties.

CLASSIFYING ATOMS

There are 92 naturally occurring elements on Earth

Elements are ordered from left to right, in order of increasing numbers of protons

The vertical columns, called groups, comprise elements that have similar chemical properties

Atomic number – number of protons an element has

Atomic mass – how heavy an element’s nucleus is; the number of protons and neutrons added together.

CHEMICAL BONDING

Compounds – two or more elements that are chemically combined

Covalent bonds – compounds that form when electrons are shared

Ionic bonds – compounds that form when electrons are transferred or moved

CHEMICAL FORMULAS

Compounds are represented by chemical formulas. These formulas include the symbol for each element followed by a subscript number.

The subscript number represents the number of atoms of that elementCO2

H2O

C6H12O6

CaCO3

STATES OF MATTER

All matter on Earth and in the universe occurs in the form of a solid, a liquid, a gas, or plasma.

Solids – substances with densely packed particles.Most solids form crystal structures

Liquids – substances with particles that slide past each other in fluid form.

Gases – substances with particles that escape the liquid when energy is added.

CHANGES OF STATE

Evaporation – change from a liquid to a gas.Condensation – change from a gas to a liquid.Sublimation – change from a solid to a gas.