Question | Answer |
matter | anything that has volume and mass |
atom | the smallest component of an element having the chemical properties of the element |
nucleus | the positively charged dense center of an atom; contains protons and neutrons |
electron cloud | a region around the nucleus of an atom where electrons are likely to be found, negatively changed |
electrical charge | a property of matter that tells whether something has a positive or negative charge |
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 and is located in the electron cloud |
subatomic particles | particles inside an atom (protons, neutrons, electrons) |
chemical formula | a combination of chemical symbols and numbers to represent a substance |
balanced equation | chemical equation with the same number of atoms of each element on both sides of the equation |
atomic mass | Total mass of the protons and neutrons in an atom, measured in atomic mass units |
atomic number | the number of protons in the nucleus of an atom |
valence electrons | electrons on the outermost energy level of an atom |
energy level | the different areas for an electron in an atom |
net charge | sum of the positive and negative charges |
property | a characteristic used to describe matter |
reactivity | the property that describes how readily a substance combines chemically with other substances |
periodic table of elements | a table with elements organized in order of increasing atomic number, and grouped such that elements with similar properties are in vertical columns. |
groups | vertical columns or families of elements on the periodic table; the elements in these have similar properties because they have the same number of valence electrons |
periods | the horizontal rows of elements in the periodic table; the elements in these have the same number of energy levels |
metalloids | elements that have characteristics of metals and nonmetals |
metals | elements that are malleable, have a shiny or metallic luster, are good conductors of heat and electricity and have a high melting point |
nonmetals | an element that is brittle, dull, tends to be a poor conductor of heat and electrictricity and a low melting point |
noble gases | the elements of group 18 of the periodic table; the least reactive group |
electron shell | the arrangement of electrons around an atom's nucleus according to the energy they contain; electrons with the least energy are in the shell closest to the nucleus, and those with more are in shells farther from the nucleus |
element | a substance that cannot be broken down into simpler substances |
atomic symbol | one or two letters that represent the name of an element; the first letter is always capitalized and other letters are always lowercase |
alkaline earth metals | Any metal in group 2A of the periodic table |
alkali metals | the elements located in group 1 of the periodic table; most reactive group on the periodic table |
halogens | The elements of Group 17, most reactive group of nonmetals on the periodic table |
subscript | number placed to the lower right of a chemical symbol to indicate the number of atoms of the element in the compound |
chemical formula | a combination of chemical symbols and numbers to represent a substance |
chemical reaction | A change in which one or more substances are converted into different substances |
chemical equation | a representation of a chemical reaction that uses symbols to show the relationship between the reactants and the products |
coefficient | A number in front of a chemical formula in an equation that indicates how many molecules or atoms of each reactant and product are involved in a reaction. |
reactants | the starting materials in a chemical reaction; located to the left of the arrow (what you start out with) |
products | the substances that are formed by the chemical reaction; located to the right of the arrow (what you end up with) |
law of conservation of mass | the law that states that mass cannot be created or destroyed |
mass | the amount of matter in an object |