Honors Chapter 3: Matter and Energy

matter

anything that has volume and mass

element

A substance that cannot be broken down into simpler substances

nucleus

Center of an atom made of protons and neutrons

proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom.

neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

Electron

A subatomic particle that has a negative charge that surround a nucleus. It has almost no mass

atomic number

the number of protons in the nucleus of an atom

mass number

the sum of the number of neutrons and protons in an atomic nucleus

isotope

Atoms of the same element that have different numbers of neutrons

ion

An atom or group of atoms that has a positive or negative charge. Positive are called cations, negative are anions.

valence electrons

electrons in the outermost shell

hydrogen and helium

The 2 most ABUNDANT ELEMENTS in the chemical composition of the universe are:

oxygen and silicon

two most abundant elements in the earth's crust

Compound

A substance made up of atoms of two or more different elements joined by chemical bonds that changes the properties of each

chemical bond

the attractive force that holds atoms or ions together

covalent bond

A chemical bond that involves sharing a pair of electrons between atoms in a molecule

ionic bond

Formed when one or more electrons are transferred from one atom to another

metallic bond

a bond formed by the attraction between positively charged metal ions and negative electrons shared between the atoms

Molecule

two or more atoms held together by covalent bonds

chemical reaction

process that changes one set of chemicals into another set of chemicals

solution

A homogeneous mixture of two or more substances

Mixture

material composed of two or more elements or compounds that are physically mixed together but not chemically combined

Acid

compound that forms hydrogen ions (H+) in solution

base

a compound that produces hydroxide ions (HO-) in solution

pH scale

scale with values from 0 to 14, used to measure the concentration of H+ ions in a solution; a pH of 0 to 7 is acidic, a pH of 7 is neutral, and a pH of 7 to 14 is basic

Plasma

hot, highly ionized, electrically conducting gas

Evaporation

The change of a substance from a liquid to a gas by an increase in thermal energy

Condensation

The change of state from a gas to a liquid by a release of thermal energy

Sublimation

A change directly from the solid to the gaseous state slowly without becoming liquid

Law of Conservation of Energy

Energy cannot be created or destroyed

polar molecule

A neutral molecule that has electrically charged areas.

endothermic reaction

A reaction that ABSORBS energy in the form of heat

exothermic reaction

A reaction that releases energy in the form of heat

synthesis reaction

a reaction in which two or more substances combine to form a new compound

decomposition reaction

a reaction in which a single compound breaks down to form two or more simpler substances