AFOQT Physical Science

Study Guide

Absolute Zero

At 0 on the Kelvin scale (-273.15 C or -459.67 F), this is the lowest temperature attainable and occurs when particles lose the maximum amount of energy.

Acid

A substance with a pH below 7. Donates protons and produces hydrogen ions in solutions.

Amplitude

The distance between the crest or trough of a wave from its resting position, or half the distance between the crest and trough of a wave.

Atmospheric pressure

Pressure exerted by Earth’s atmosphere. At sea level, standard atmospheric pressure is 100 kPa (kilopascals), 1atm (atmospheres), 760 mm Hg (millimeters of mercury), or 760 Torr.

Atom

The smallest particle that exists of any given element. It consists of a nucleus (containing protons and neutrons) and the surrounding electrons.

Atomic Mass

The mass of one atom of an element measured in amu and is determined by the mass of 1/12 of a carbon-12 atom.

Atomic Number

The identifying number of an element on the periodic table, which is equal to the number of protons in the nucleus.

Atomic Weight

Different than the atomic mass, this is the weighted average mass of all isotopes of an element.

Base

A substance with a pH above 7. They accept protons and produce hydroxide ions into solutions.

Boiling Point

The temperature at which the molecules of a substance have enough energy to switch from the liquid phase to the gas phase.

Celsius Scale

One of the three main temperature scales. This scale determines the freezing point of water to be zero degrees and the boiling point at 1 atm, to be 100 degrees.

Change of State

Matter can exist in several states or phases including Bose-Einstein condensate, solid, liquid, gas, and plasma. This is when one changes from one of these phases to another.

Compound

Two or more elements chemically bonded together like NaCl (salt).

Condensation

An exothermic phase change that results in a gas cooling into a liquid.

Conduction (Electrical)

The process of electrons flowing through conductive matter

Conduction (Heat)

The process of heat energy moving from a warmer object to a cooler object through physical contact.

Convection

The transfer of heat through a fluid (liquid or gas) caused by hotter (and therefore less dense) material rising and colder (more dense) material sinking.

Covalent Bond

A chemical bond formed when atoms share electrons.

Decay (Radioactive Decay)

Radiation causing the loss of mass. The result of this process is the changing of one element into another like Bismuth-210 decomposes to Polonium-210 through beta-emission.

Density

A measure of the closeness of particles in a substance, which is found by dividing the mass of the substance by the volume it occupies. Units are typically grams per cubic centimeter (g/cm³).

Diffusion

The process of particles of two or more substances moving until equally distributed and mixed together. The rate of diffusion is determined by the concentrations of the substances and the energy in the particles.

Dissolve

When components of a substance separate and move throughout a liquid, but do not chemically react with the liquid.

Electric Potential

Defined as the amount of work required to move a unit of electric charge from a reference point to a specific point within an electric field. Also called voltage, measured in volts.

Electron

A subatomic particle with a negative electrical charge that is not part of the nucleus.

Element

One of the ~100 basic substances that cannot be broken down chemically into a simpler substance.

Energy

The ability to do work or produce heat.

Explosive

A property that allows for a very quick, almost instant, decomposition of a substance with the release of a large amount of energy.

Force

A push or pull on an object.

Fluid

A substance that has molecules that are able to flow past one another. It include liquids, gases, and plasmas.

Freezing Point

An exothermic phase change from liquid to solid. The melting point is the endothermic phase change that happens at the same temperature.

Frequency

A measure of the number of waves that pass a specific point per second.

Gamma Rays

Damaging waves of radiation produced by the release of photons from the nucleus of a radioactive element.

Gas/Gaseous Phase

Phase of matter where molecules have enough energy to break the bonds attracting them to one another.

Gravity

The attractive force that exists between any two physical objects that have mass.

Group

Also known as a family. Columns on the periodic table are known as ____ and share similar chemical properties based on the number of valence electrons they have in common.

Half-Life

The amount of time that it takes for a radioactive element to lose half of its radiation.

Heat

The transfer of energy as the result of a temperature difference between a substance and its environment. ___ always flows from higher energy to lower energy.

Heat Capacity

The amount of heat needed by a substance to result in a change in temperature. ____ is mass-dependent while “specific _____” is not.

Heat of Combustion

A property of a substance that indicates the amount of heat that is released when one mole of the substance combusts. Each substance has a specific “_______”.

Hertz (Hz)

The unit of measurement for wave frequency, which measures wave cycles per second.

Ion

A charged atom. Negatively charged “____“ (anions) are atoms that have more electrons that protons. Positively charged ____ (cations) are atoms that have fewer electrons than protons. The movement of electrons during ion formation can cause an electric field.

Ionic Bond

A chemical bond formed by the attraction of oppositely charged ions.

Isotope

Atoms of the same element that have a different number of neutrons. For instance, carbon-12 has 6 protons and 6 neutrons while its isotope, carbon-14 has 6 protons and 8 neutrons.

Kinetic Energy

The energy of motion.

Latent Heat

The amount of heat that a substance will absorb or release during a phase change while the temperature remains constant.

Lens

A transparent object with a curved surface that causes light to bend.

Liquid/Liquid Phase

The phase of matter where molecules have enough energy to move past one another, but not break the bonds attracting them to one another. _____ do not have a fixed shape but do have fixed volume.

Mass

The amount of matter an object contains.

Matter

Defined as anything that has mass and takes up space, meaning it has volume.

Medium

The material through which a wave travels.

Melting Point

An endothermic phase change from solid to liquid. The freezing point is the the exothermic phase change that happens at the same temperature.

Metal

An element that releases electrons and creates a positive ion (cation). ____ are good conductors of electricity and heat. Known for being malleable and ductile, and have a ____lic luster. The cations of transition ____ exist in a sea of free-floating electrons, which gives their unique properties.

Mixture

A combination of two or more substances that can be separated by physical means.

Mole

is a unit of measurement used to express amounts of a chemical substance. It's defined as containing exactly 6.02214076×1023 elementary entities (such as atoms, molecules, ions, or electrons). This number is known as Avogadro's number.

Molecule

The smallest group of chemically-bonded atoms that can exist and still react and retain the properties of a substance.

Neutron

A neutral (no charge) subatomic particle that exists inside the nucleus of an atom.

Newton (N)

A unit of force that is equal to 1 kilogram metter per second squared. (N)

Noble Gases

A group of elements in the far right column of the periodic table, known for being unreactive.

Nucleus

The center of the atom which contains the protons and neutrons.

Ohm

The units that describe the electrical resistance of a conductor.

Particle

A small piece of matter.

Period

One of eight horizontal rows on the periodic table.

Periodic Table

An organizational chart of all of the known elements in order of increasing atomic number (# of protons).

pH

A measurement of the hydrogen ion concentration in a solution.

Phase

A state of matter dependent on the amount of energy in a substance’s molecules. Most common are solid, liquid, and gas.

Photon

A particle with zero mass that transmit light or other electromagnetic radiation.

Potential Energy

The energy an object holds due to its position relative to other objects.

Pressure

The amount of force exerted per given area, measured in pascals (Pa).

Proton

A positively charged subatomic particle in the nucleus of an atom. The number of protons in a nucleus determines an element’s atomic number.

Radiation

Heat energy moving from a warmer object to a cooler object through waves. It is the only form of heat transfer which does not require a medium.

Solid/Solid Phase

The phase of matter where molecules do not have enough energy to move past one another, which forces a fixed shape and volume.

Wave

An energy-carrying disturbance