Bio Ch 2

Front 1

Element

Back 1

a substance that cannot be broken down to other substances by chemical reactions.

Front 2

Compound

Back 2

substance consisting of two or more different elements combined in a fixed ratio.

Front 3

matter

Back 3

anything that takes up space and has mass.

Front 4

Trace elements

Back 4

those required by an organism in only minute quantities Ex: lack of iodine cause goiters

Front 5

neutron

Back 5

a subatomic particle having no electrical charge (electrically neutral). Found in the nucleus of an atom.

Front 6

protons

Back 6

a subatomic particle with a single positive electrical charge. Found in the nucleus of the atom.

Front 7

electrons

Back 7

a subatomic particle with a single negative electrical charge . Moves around the nucleus of the atom.

Front 8

atomic nucleus

Back 8

an atom's dense central core, containing protons and neutrons.

Front 9

atomic number

Back 9

the number of Protons in the nucleus of the atom, unique for each element.

Front 10

mass number

Back 10

the sum of the number of Protons and Neutrons in an atom's nucleus.

Front 11

atomic mass

Back 11

the total mass of an atom, which is the mass in grams of 1 mole of the atom

Front 12

isotopes

Back 12

one of several atomic forms of an element, each with the same number of protons but a different number of neutrons thus differing in atomic mass.

Front 13

radioactive isotope

Back 13

an isotope that is unstable; the nucleus decays spontaneously, giving off detectable particles and energy.

Front 14

Energy

Back 14

the capacity to cause change, especially to do work

Front 15

Potential energy

Back 15

the energy that matter possess as a result of its location or spatial arrangement (structure).

Front 16

electron shells

Back 16

an energy level of electrons at a characteristic average distance from the nucleus of an atom.

Front 17

valence electrons

Back 17

an electron in the outermost electron shell

Front 18

orbital

Back 18

the three-dimensional space where an electron is found 90% of the time.

Front 19

chemical bonds

Back 19

an attraction between two atoms, resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms. The bonded atoms gain complete outer electron shells.

Front 20

molecule

Back 20

two or more atoms held together by covalent bonds

Front 21

single bond

Back 21

a single covalent bond; the sharing of a pair of valence electrons by two atoms

Front 22

structural formula

Back 22

a type of molecular notation in which the constituent atoms are joined by lines representing covalent bonds.

Front 23

molecular formula

Back 23

a type of molecular notation representing the quantity of constituent atoms, but not the nature of the bonds that join them.

Front 24

double bond

Back 24

a double covalent bond; the sharing of two pairs of valence electrons by two atoms.

Front 25

valence

Back 25

the bonding capacity of a given atom, usually equals the number of unpaired electrons required to complete the atom's outermost shell

Front 26

electronegativity

Back 26

the attraction of a given atom for the electrons of a covalent bond

Front 27

nonpolar covalent bond

Back 27

covalent bond in which electrons are shared equally between two atoms of similar electronegativity.

Front 28

polar covalent bond

Back 28

covalent bond between atoms that differ in electronegativity; the shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive.

Front 29

ion

Back 29

an atom or group of atoms that has gained or lost one or more electrons, thus acquiring a charge.

Front 30

cation

Back 30

a positively charged ion

Front 31

anion

Back 31

a negatively charged ion

Front 32

ionic bond

Back 32

chemical bond resulting from the attraction between oppositely charged ions

Front 33

ionic compounds (salts)

Back 33

compound resulting from the formation of an ionic bond.

Front 34

hydrogen bond

Back 34

weak chemical bond that is formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule.

Front 35

van der Waals interactions

Back 35

weak attractions between molecules that result from localized charge fluctuations.

Front 36

reactant

Back 36

a starting material in a chemical reaction

Front 37

products

Back 37

a material resulting from a chemical reaction.

Front 38

chemical reactions

Back 38

the making and breaking of chemical bonds, leading to changes in the composition of matter.

Front 39

chemical equilibrium

Back 39

the state in which the rate of the forward reaction equals the rate of the reverse reaction, so that the relative concentrations of the reactants and products do not change with time.