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 = O Carbon = 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 atoms Each atom consists of three subatomic particles: ParticleChargeLocation ProtonsPositiveNucleus NeutronsNo chargeNucleus ElectronsNegativeAround 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 nucleus The 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 element CO 2 H 2 O C 6 H 12 O 6 CaCO 3

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.