 | Term | Definition |
| |
atom |
the smallest unit of an element that maintains the properties of that element |
| |
electron |
a subatomic particle that has a negative charge |
| |
nucleus |
in physical science, an atom's central region, which is made up of protons and neutrons |
| |
electron cloud |
a rgion around the nucleus of an atom where electrons are likely to be found |
| |
proton |
a subatomic particle that has a positive charge and that is found in the nucleus of an atom |
| |
atomic mass unit |
a unit of mass that describes the mass of an atom or molecule |
| |
neutron |
a subatomic particle that has no charge and that is found in the nucleus of an atom |
| |
atomic number |
the number of protons in the nucleus of an atom; all the atomic number is the same for all the atoms of an element |
| |
isotope |
an atom that has the same number of protons as other atoms of the same element but has a differernt number or neutrons |
| |
mass number |
that sum of the numbers of protons and neutrons in the nucleus of an atom |
| |
atomic mass |
the mass of an atom expressed in atomic mass units |
| |
periodic |
describs something that occurs or repeats at regular intervals |
| |
periodic law |
the law that states that the repeating chemcal and physical properties of elements change periodically with the atomic number o the elements |
| |
period |
in chemistry, a horizontal row of elements in the periodic table |
| |
group |
a vertical column of elements in the periodic table; elements in a group share chemical properties |
| |
alkali metal |
group 1 |
| |
alkaline- earth metal |
group 2 |
| |
halogens |
group 17 |
| |
noble gas |
group 18 |
| |
chemical bonding |
the combining of atoms to form molecules or ionic compounds |
| |
chemical bond |
an interactiont hat holds atoms or ions together |
| |
valence electron |
an electron that is found in the outermost chell of an atom and that determines that atom's physical properties |
| |
ionic bond |
a bond that forms when electrons are transferred from one atom to another, which results in a positive ion and a negative ion |
| |
ion |
a changed particle that forms when an atom or a group of atoms gains or loses one or more electrons |
| |
crystal lattice |
the regular pattern in which a crystal is arranged |
| |
covalent bnd |
a bond formed when atoms share one or more pairs of electrons |
| |
molecule |
the smallest unit of a substance that keeps all of the physical and chemical properties of that substance |
| |
metallic bond |
a bond formed by the attraction between positively charged metal ions and the electrons around them |
| |
chemical reaction |
the process by which one or more substances change to produce one or more different substances |
| |
precipitate |
a solid that is produced as a result of a chemical reaction in solution |
| |
chemical formula |
a combination of chemical symbols and numbers to represent a substance |
| |
chemical equation |
a representation of a chemical reaction that uses symbols to show the relationship between the reactants and the products |
| |
reactant |
a subtance or molecule that participates in a chemical reaction |
| |
product |
the substnace that forms in a chemical raction |
| |
synthesis reaction |
a reaction in which two or more substances combine to form a new compund |
| |
decomposition reaction |
a reaction in which a single compound breaks down to form two or more simpler substances |
| |
single-displacement reaction |
a reaction in which one element or radical takes the place of another element or radical in a compound |
| |
double-displacement reaction |
a reaction in which gas, a solid precipitate, or molecular compound forms from the exchange of ions between two compounds |
| |
exothermic reaction |
a chemical reaction in which heat is released to the surroundings |
| |
endothermic reaction |
a chemical reaction that requires heat |
| |
law of conservation of energy |
the law that states the energy can not be created or destroyed but can be changed from one form to another |
| |
activation energy |
the minimum amount of energy required to start a chemical reaction |
| |
chemical bond |
the combining of atoms to form molecules or compounds |
| |
ionic compound |
a compound made of oppositely charged ions |
| |
covalent compound |
a chemical compound formed by the sharing of eletrons |
| |
acid |
any compound that increases the number of hydrogen ions when dissolved in water |
| |
indicator |
a compound that can reversibly change color depending on conditions such as pH |
| |
base |
any compound that increases the number of hydroxide ions when dissolved in water |
| |
neutralization reaction |
the reaction of an acid and a base to form a neutral solution of water and salt |
| |
pH |
a value that is used to express the acidity or basicity of a syestem |
| |
salt |
an ionic compound that forms when a metal atom replaces the hydrogen of an acid |
| |
organic compound |
a covalently bonded compound that contains carbon |
| |
hydrocarbon |
an organic compound composed only of carbon and hydrogen |
| |
carbohydrate |
a class of energy giving nutrients that includes sugars, starches, and fiber; composed of one or more simple sugars bonded together |
| |
lipid |
a type of biochemical that does not dissolve in water; fats and steroids are lipids |
| |
protein |
a molecule that is made up of amino acids and that is needed to build and repair body structures and to regulate processed in the body |
| |
nucleic acid |
a molecule made up of subunits called nucleotides |
| |
radioactivity |
the process by which an unstable nucleus gives off nuclear radiation |
| |
mass number |
the sum of the numbers of protons and neutrons in the nucleus of an atom |
| |
isotope |
an atom that has the same number of protons as other atoms of the same element do but that has a different number of neutrons |
| |
half-life |
the time needed for half of a sample of a radiocative substance to undergo radioactive decay |
| |
nuclear fission |
the splitting of the nucleus of a large atom into two or more fragments; releases additional neutrons and energy |
| |
nuclear chain reaction |
a continuous series of nuclear fission reactions |
| |
nuclear fusion |
the combonation of the nuclei of small atoms to form a larger nucleus; releases energy |
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