Vocabulary

All Classes

This vocabulary list will be updated to include the most recent terms as the semester progresses. Words and terms easily found in your textbook will most likely not be included. Keep your eyes open for links (underlined text) that will help to clarify definitions.

activation energy: the minimum amount of energy required to convert a normal stable molecule into a reactive molecule

atomic symbol: a notation using one to two letter to represent an element; the first letter is always upper case and the second lower case

balanced chemical equation: when there are an equal number of atoms of each element on both sides of a chemical equation

billiard ball atomic model: the first model of an atom; developed in 1803 by (John) Dalton; Dalton observed that the gases of air could be compressed only so far and concluded that air and all other matter is composed of solid, indestructable particles (atoms) too tiny to see

binary compound: a compound composed of only two elements

Bohr atomic model: developed by (Niels) Bohr in 1922; Bohr discovered fixed energy levels for electrons and developed the model of the atom that shows electrons "orbiting" around the nucleus in fixed orbits (valence shells), much like the layers of an onion

Boyles Law: the gas law that describes the relationship between pressure and volume; for a fixed amount of gas at a constant temperature, pressure and volume are inversely proportional (For a more detailed explanation that might help clarify this law, click here.)

catalyze: to modify, especially to increase, the rate of a chemical reaction

cellulose: a complex carbohydrate, (C₆H₁₀O₅)_n, that is composed of glucose units, forms the main constituent of the cell wall in most plants; humans lack the ability to digest it

Charles Law: the gas law that describes the relationship between volume and temperature; at constant pressure, volume and temperature are directly proportional (For practice using this law click here, but these problems are tough!)

chemical equation: a symbolic representation of a chemical reaction; reactants are on the left side of the equation, and products are on the right

chemical reaction: the process by which one or more substances are changed into others

coefficient: the large script number that precedes an element, compound, or molecule that tells you the number of atoms of each element that follows it

compound: two or more atoms chemically combined

condensation: the process by which a gas becomes a liquid; energy is decreased enough so that the attractive forces between molecules forces molecules into near proximity

dew point: the point of saturation

direct relationship: the relationship between two variables where both variables change in the same direction to the same degree

electron cloud atomic model: a cloud-like model of the atom that describes where an electron is likely to be found; (Erwin) Schrödinger took Bohr's model a little further by applying a probability equation to the movements of electrons; it can not say with any certainty where the electron actually is at any point in time, yet can describe where it ought to be; the probable locations of the electron predicted by Schrödinger's equation happen to coincide with the locations specified in Bohr's model

element: substance that can not be broken down to a simpler substance by ordinary chemical means

energy levels: the orbital paths an electron follows around the nucleus of an atom; the first level can hold up to two electrons, while all other levels can hold up to eight electrons

evaporation: the process by which a liquid becomes a gas; enough energy is gained so that molecules can escape the surface of the liquid

freezing: process by which a liquid becomes a solid; enough energy is removed so that the attractive forces between molecules holds them in fixed positions

humus: the brown or black organic substance in soil consisting of partially or wholly decayed vegetable or animal matter that provides nutrients for plants and increases the ability of soil to retain water

ion: an electrically charged atom

ionic compound: a coumpound that is formed by ionic bonds

inference: a conclusion derived from observations and/or previous experience

inverse relationship: the relationship between two variables where one variable changes in one direction and the other variable changes in the opposite direction to the same degree

molecule: a neutral group of atoms held together by covalent bonds

melting: process by which a solid becomes a gas; enough energy is gained to overcome the attractive forces that hold molecules in fixed positions

observation: facts about something gained through the use of the five senses

orbit: the path of a celestial body or an artificial satellite as it revolves around another body

oxidation number: the apparent charge on an atom that indicates its charge after electrons are gained or given up; written as a superscript (ex: Na³⁺)

point of saturation: the point at which the air can hold no more water; this is also known as the dew point

polyatomic ion: a group of atoms covalently bonded but possessing an overall charge

polymer: a chemical compound or mixture of compounds formed by polymerization and consisting essentially of repeating structural units

qualitative: information about something using descriptive words (non-numerical)

quantitative: information about something that describes how much (numerical)

R group: the part of a protein that is the chemical variable where different functional groups can be present; determines the different amino acids

subscript: the small number behind and below an element that tells you the number of atoms of the preceding element only; in the case of a subscript behind parentheses, the subscript applies to all elements within the parentheses

sublimation: the process by which a solid becomes a gas without ever becoming a liquid; enough energy is gained so that molecules can escape the surface of the solid and go into the air

blueberry muffin atomic model: also known as the "plum pudding" model; developed in 1897 by (Joseph John) Thompson as an improved model of the atom that included particles (electrons) scattered throughout the solid mass of an atom; he had proven the existence of electrons as part of an atom through experiments with the cathode ray tube