Science Finals

Im going to. kill myself

Substance

A single kind of matter that is pure and has a specific set of properties.

Physical Property

A characteristic of a pure substance that can be observed without changing it into another substance

Chemical Property

A characteristic of a pure substance that describes its ability to change into different substances

Element

A substance that cannot be broken down into simpler substances

Atom

The basic particle from which all elements are made

Molecule

a group of two or more atoms held together by chemical bonds

Compound

A substance made of two or more elements that are chemically combined in a set ratio.

Mixture

A combination of two or more substances that are not chemically combined

Weight

A measure of the gravitational force exerted on an object.

Mass

the amount of matter in an object

Volume

The amount of space that matter occupies

Density

A measure of the mass of material in a given volume

Physical Change

Alters the form or appearance of a matter but does not turn any substance in the matter into a different substance

Chemical Change

A change in matter that produces one or more new substances

Law of Conversation of mass

The fact that matter is not created or destroyed in any chemical or physical change.

Temperature

A measurement of how hot or cold something is. It is related to the energy of motion of the particles of matter

Thermal Energy

The total energy of motion of all of the particles in an object

Endothermic Change

a change in which energy is absorbed

Exothermic Change

a change in which energy is released

Chemical Energy

The energy stored in the chemical bonds between atoms is a force of energy

Solid

A form of matter that has a definite shape and volume

crystalline solid

A solid that is made up of crystals in which particles are arranged in a regular, repeating pattern

amorphous solid

A solid made up of particles that are not arranged in a regular pattern

liquid

A state of matter that has no definite shape but has a definite volume.

Fluid

A substance that flows

surface tension

Inward force, or pull, among the molecules in a liquid that brings the molecules on the surface closer together

Viscosity

A liquid's resistance to flowing

Gas

A state of matter with no definite shape or volume

Pressure

The force of its outward push divided by the area of the walls of the container (P=F/A=PA)

Temperature

Measurement of the average energy of a random motion of the particles of matter

Melting

The change in state from a solid to a liquid

Brownian motion

erratic movement of colloid particles in a solid

absolute zero

The temperature at which no more energy can be removed from matter, 0 Kelvin (-273 C)

Melting point

The temperature at which a solid becomes a liquid, its particles vibrate so fast that they break free from their fixed positions

Freezing

The change of state from a liquid to a solid

Freezing point

At a liquids freezing point, its particles are moving so slowly that they begin to take on fixed positions

Vaporization

The change of state from a liquid to a gas, this only occurs when the particles in a liquid gain enough energy to move independently

Evaporation

Vaporization that takes place only on the surface of a liquid

Boiling

Vaporization that occurs on and below the surface of a liquid

boiling point

The temperature at which a liquid boils

Condensation

The change in state from a gas to a liquid, occurs when particles in a gas lose enough thermal energy to form a liquid

Sublimation

When the surface particles of a solid gain enough energy that they form a gas

Lussac's Law

When the temperature of a gas at a constant volume is increased, the pressure of the gas increases. When the temperature is decreased, the pressure of the gas decreases

Charles' Law

When the temperature of a gas at constant pressure is increased, its volume increases. When the temperature of a gas at constant pressure is decreased, its volume decreases.

directly proportional

a term used to describe the relationship between two variables whose graph is a straight line passing through the point (0,0)

Boyle's Law

When the pressure of a gas at constant temperature is increased, the volume of the gas decreases. When the pressure is decreased, the volume increases.

inversely proportional

the relationship between two variables whose product is constant

**Electron**

The negatively charged particles in an atom

**Nucleus**

The positivly charged center of an atom that contains nutrons and protons

**Proton**

Posotivly charged particles on an atoms nucleus

**Energy** **Level**

Specific amount of energy on electrons movement has

**Neutron**

Exists in the nucleus of the atoms, no electrical charge, and contains the mass of the atom.

**Atomic** **Number**

The number of protons in the nucleus of an atom

**Isotope**

An atom with the same number of protons and a different number of neutrons from other atoms of the same element

**Mass** **Number**

The sum of protons and neutrons

**Atomic** **Mass**

The average mass of all the isotopes of an elemen

**Chemical Symbol**

A one- or two letter representation of an element

**Period**

The horizontal rows in the periodic table.

**Group/families**

The vertical columns in the periodic table.

**Metal**

a class of elements characterized by physical properties that includes luster, malleability, ductility, and conductivity

**Luster**

The amount of shine a metal has

**Malleable**

When a metal has the ability to be flattened.

**Ductile**

When a metal has the ability to be pulled into a wire

**Thermal Conductivit**y

The ability of an object to transfer heat

**Electrical Conductivity**

How easily an object allows electrical current to flow through it

**Reactivity**

The ease and speed with which an element combines, or reacts, with other elements and compounds

**Corrosion**

The gradual wearing away of a metal element due to chemical reaction

**Alkali** **Metal**

The metals in group 1 except Hydrogen, they are very reactive

**Alkaline** **Earth** **Meta**

group 2, harder denser, melt at higher temps, reactive

**Transition** **Metal**

groups 3-12, iron, copper, gold, silver, hard, shinny, high melting points, high densities, good conductors of heat and electricity, less reactive

**Lanthanides**

top row under main table

**Actinides**

below the lanthanides, artifical

**Transuranium** **Elements**

elements that follow uranium, made when nuclear particles are forced to crach with one another, synthetic

**Nonmetal**

right side, poor conductors of heat and electricity, dull and brittle, low densities, gases, share electrons

**Diotomic** **Molecule**

A molecule that has two of the same element, like oxygen (O2)

**Halogen**

nonmetals, fluorine, chlorine, bromine, iodine, group 17, and very reactive

**Noble** **Gas**

nonmetals, helium, neon, argon, krypton, xenon, radon, group 18, nonreactive due to 8 valence electrons

**Hydrogen** **Family**

group 1, simplest atom, just hydrogen

**Carbon** **Family**

nonmetal carbon, group 14

**Nitrogen** **Family**

nonmetals nitrogen and phosphorus, group 15, diatomic molecule

**Oxygen** **Family**

nonmetals oxygen, sulfur, selenium, group 16

**Metalloid**

Have some properties of metals and nonmetals, they are solids at room temp, brittle, hard, somewhat reactive, conductivity depends on temp, lighting, or presence of impurities

**Semiconductor**

Can conduct electric currents in some conditions but not others (they are metaliods)

**Radioactive** **Decay**

The atomic nuclei of radioactive isotopes release fast moving particles and energy which cause the identity of the atom to change

**Nuclear** **Reaction**

Turns one element into another

**Radioactivity**

the spontaneous emission of radiation by an unstable atomic nucleus

**Alpha** **Particicle**

decreases teh atomic number by 2 and the mass by 4 because it goves off 2 neutrons and protons

**Beta** **Particle**

A fast moving electron given off by a nucleus during radioactive decay (mass stays the same one more proton one less neutron and atomic number increases by one)

**Gamma Ray**

Does not change the mass or atomic number

**Half**-**Life**

the time it takes for half of the atoms of a radioactive element to decay

**Radioactive** **Dating**

the process of determining the age of an object using the half-life of one or more radioactive isotopes

**Valence** **Electron**

the electrons in the highest energy level of an atom that are involved in chemical bonding

**Electron** **Dot** **Diagram**

a representation of the valence electrons in an atom, using dots as the electrons

**Chemical** **Bond**

The force of attraction that holds 2 atoms together

**Ion**

an atom or group of atoms that has an electric charge

**Polyatomic** **Ion**

ions made of one or more atom

**Ionic** **Bond**

the attraction between two positively charged ions

**Ionic** **Compound**

A compound that consists of positive and negative ions that give and take electrons

**Subsript**

 The little number on the bottom right of the symbolof the element, it tells the amount of that element that is needed for the compound

**Covalent Bond**

the chemical bond formed what two atoms share electrons