Chem vocab ch. 4

element symbol

letter code for an element that is usually one to two letters long

law of constant composition

a given compound always contains elements in exactly the same proportion by mass

Daltons Atomic Theory

theory established by John Dalton in the early 1800's, used to explain the nature of materials

Atom

fundamental units of which elements are composed

compound

substance made of 2 or more different elements joined together in a specific way

chemical formula

representation of a molecule in which the symbols for the elements are used to indicate the types of atoms present and subscripts are used to show the relative numbers of atoms

electron

negatively charged subatomic particles

nucleus

the relatively small and dense center of positive charge in an atom

proton

positively charged subatomic particle located in the atomic nucleus

neutrons

a subatomic particle in the atomic nucleus with no charge

isotope

atoms with the same number of protons but different numbers of neutrons

atomic number

the number of protons in the nucleus of a given space

mass number

total number of protons and neutrons in the nucleus of a given atom

periodic table

chart showing all the elements arranged in columns in such a way that all the elements in a given column exhibit similar chemical properties

group

vertical columns of elements on the periodic table

alkali metal

group 1A metals

alkali earth metals

group 2A metals

halogen

group 7A elements

nobel gas

group 8A elements

transition metal

several aeries of elements in which inner orbitals are being filled

metal

an element that gives up electrons relatively easily and is typically lustrous, malleable and a good conductor of energy and heat

nonmetal

element that doesnt exhibit metallic characteristics; chemically a typical nonmetal accepts electrons from a metal

metalloid

element that has both metallic, and nonmetallic properties

law of conservation of mass

mass is neither created nor destroyed

ion

an atom/ group of atoms that has a positive or negative charge

cation

positively charged ion

anion

a negatively charged ion

ionic compound

a compound that results when a meta reacts with a nonmetal to form cations and anions