A charged particle that is formed when electrons are gained or lost
isotopes
Atoms of the same element with different number of neutrons
atomic number
The number of protons in the nucleus of an atom
mass number
The sum of the number of protons and neutrons in an atom
atomic mass
The average of the masses in an element’s isotopes
oxidation number
A number that indicates an element’s charge
chemical bonds
A force that holds atoms together in molecules
ionic bonds
A bond formed by an electron transfer
electron
A negatively charged particle in an atom
covalent bond
A bond formed by sharing electrons
valence electrons
The electrons in the outermost energy levels often involved in bonding
periodic table
A chart in which elements are grouped according to their properties and increasing mass numbers
periods
The seven numbered horizontal ( > ) rows on the Periodic Table. Elements within each period have: 1- different chemical and physical properties 2- different number of electrons in the outer energy level 3- same number of energy levels
groups
The eighteen numbered vertical ( ^ ) rows on the Periodic Table. Elements in the same group have: 1- • similar chemical and physical properties 2- same number of electrons in their outer energy level 3- different number of energy levels
metals
Elements that are:1 - shiny 2- good conductors of heat & electricity 3 - malleable 4 - tend to lose electrons in chemical reactions 5 - are found on the left side of the Periodic Table
nonmetals
nonmetals - Elements that : 1 - lack luster (not shiny) 2 - are poor conductors heat and electricity 3 - are not malleable 4 - tend to gain electrons in chemical reactions 5 - found on the right side of the Periodic Table
noble gases
Relatively inactive inert elements found in group 18
Law of Conservation of Mass
A law that states that in a chemical reaction, the total mass of the reactants equals the total mass of the products
chemical reaction
A process in which bonds break apart and combine into new kinds of matter with different properties
reactant
The starting substances in a chemical reaction
product
The new substance(s) that are formed in a chemical reaction
precipitate
A solid that separates from a solution
activation energy
The energy required to break the bonds in a chemical reaction
exothermic reaction
A chemical reaction that releases energy
endothermic reaction
A chemical reaction that absorbs energy
chemical symbol
A one or two letter abbreviation for an element
chemical formula
A group of symbols that shows the makeup for a compound
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