Chapter 2: Vocabulary

Question 1

matter

Answer 1

anything that occupies space and has mass

Question 2

element

Answer 2

a substance that cannot be broken down to other substances by chemical means. Scientists recognize 92 chemical elements occurring in nature

Question 3

trace elements

Answer 3

an element that is essential for the survival of an organism but only in minute quantities

Question 4

compound

Answer 4

a substance containing @ or more elements in a fixed ratio. For example, table salt (NaCl) consists of one atom of the element sodium (Na) for every atom of chlorine (Cl)

Question 5

atom

Answer 5

the smallest unit of matter that retains the properties of an element

Question 6

proton

Answer 6

A subatomic particle with a single positive electrical charge, found inside the nucleus of an atom

Question 7

neutron

Answer 7

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

Question 8

electron

Answer 8

A subatomis particle with a single negative electrical charge. One or more electrons move around the nucleus of an atom

Question 9

nucleus

Answer 9

(!) An atom’s central coe, containing protons and neutrons (2) The genetic control center of a eukaryotic cell.

Question 10

atomic number

Answer 10

the number of protons in each atom of a particular element

Question 11

atomic mass

Answer 11

the approximate total mass of an atom; also called atomic weight. Given as w whole number, the atomic mass approximately equals the mass number

Question 12

mass number

Answer 12

the sum of the number of protons and neutrons in an atom’s nucleus

Question 13

isotipe

Answer 13

a variant form of an atom. isotopes of an element have the same number of protons but different numbers of neutrons

Question 14

radioactive isotope

Answer 14

an isotope whose nucleus decays spontaneously, giving off particles and energy

Question 15

electron shell

Answer 15

an energy level representing the distance of an electron from the nucleus of the atom

Question 16

chemical bond

Answer 16

an attraction between 2 atoms resulting from a sharing of outer-shell electrons or the prescence of opposite charges on the atoms/ The bonded atoms gain complete outer electron shells

Question 17

ion

Answer 17

an atom or molecule that has gained or lost 1 or more electrons, thus acquiring an electrical charge

Question 18

ionic bond

Answer 18

an attraction between two ions with opposite electrical charges. The electrical attraction of the opposite charges holds the ions together

Question 19

salt

Answer 19

a compound resulting from the formation of ionic bonds; also called an ionic compound

Question 20

molecule

Answer 20

a group of 2 or more atoms held together by covalent bonds

Question 21

double bond

Answer 21

a type of covalent bond in which 2 atoms share 2 pairs of electrons; symbolized by a pair of lines between the bonded atroms

Question 22

electronegativity

Answer 22

the tendency for an atom to pull electrons towards itselg

Question 23

plar covalent bond

Answer 23

an attraction between atoms that share electrons unequally because the atoms differ in electronegativity. the shared electrons are pulled closer to the more electronegative atom, making it partially negative and the other atom partially positive

Question 24

polar molecule

Answer 24

a molecule containing polar covalent bonds

Question 25

hydrogen bond

Answer 25

a type of weak chemical bond formed when the partially positive hydrogen atom participating in a polar covalent bond in one molecule is attracted to the partially negative atom participating in a polar covalent bond in another molecule ( or in another part of the same macromolecule)

Question 26

surface tension

Answer 26

a measure of how difficult it is to stretch or break the surface of a liquid

Question 27

heat

Answer 27

thermal energy; the amount of energy associated with the movement of atoms and molecules in a body of matter. heat is energy in its most random fotrm

Question 28

temperature

Answer 28

a measure of the intensity of heat, reflecting the average kinetic energy or speed of molecules

Question 29

solution

Answer 29

a liquid consisting of a homogeneous mixture of 2 or more substances, consisting of a dissolving agent, called the solvent, and a substance that is dissolved, called the solute

Question 30

solute

Answer 30

a substance that is dissolved in a solution

Question 31

solvent

Answer 31

the dissolving agent in a solution. water is the most versatile known solvent.

Question 32

aqueous solution

Answer 32

a solution in which water is the solvent

Question 33

acid

Answer 33

a substance that increases the hydrogen ion concentration in a solution

Question 34

base

Answer 34

a substance that decreases the hydrogen ion (H+) concentration in a solution

Question 35

buffer

Answer 35

a chemical substance that resists changes in pH by accepting hydrogen ions forom or donating hydrogen ions to solutions

Question 36

pH scale

Answer 36

the measure of relative acidity of a solution, ranging in value from 0 (most acidic) to 14 (most basic). The letters pH stand for potential hydrogen and refer to the concentration of hydrogen ions (H+)

Question 37

acid precipitation

Answer 37

rain, snow, sleet, hail, drizzle and so on with a pH below 5.6. Acid precipitation can damage or destroy organisms by acidifying lakes, streams, and possibly land habitats

Question 38

chemical reaction

Answer 38

a process leading to changes in the composition of matter; involves the making and/or breaking of chemical bonds

Question 39

reactants

Answer 39

a skating material in a chemical reaction

Question 40

product

Answer 40

an ending material in a chemical reaction

Question 41

covalent bond

Answer 41

an attraction between atoms that share one or more pairs of outer shell electrons; symbolized by a single line between the atoms

Question 42

non polar covalent bond

Answer 42

an attraction between atonst that share one or more electrons equally because the atoms have similar electronegativity

Question 43

cohesion

Answer 43

tha attraction between molecules of the same kind