Chem. Basis Of Life

Question 1

A substance consisting of two or more different elements combined in a fixed ratio. More common than pure elements.

Answer 1

Compound

Question 2

An element that is essential for life but required in extremely minute amounts.

Answer 2

Trace elements

Question 3

Smallest unit of matter that still retains the properties of an element. From Greek word meaning “indivisible”.

Answer 3

Atom

Question 4

A subatomic particle with a single positive charge. (+)

Answer 4

Proton

Question 5

A subatomic particle with a single negative charge. (-)

Answer 5

Electron

Question 6

A subatomic particle having no electrical charge, found in the nucleus of an atom.

Answer 6

Neutron

Question 7

(1) An atoms central core, containing protons and neutrons.

(2) The organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made of chromatin.

Answer 7

Nucleus (nuclei)

Question 8

The number of protons in each atom of a particular element.

Answer 8

Atomic number

Question 9

The sum of the number of protons and neutrons in its nucleus

Answer 9

Mass number

Question 10

One of several atomic forms of an element, each with the same number of protons and behave Identically in chemical reactionS, but a different number Of neuTrOns.

Answer 10

Isotopes

Question 11

An isotope whose nucleus decays spontaneously, giving of particles and energy

Answer 11

Radioactive isotope

Question 12

A level of electrons at a characteristic average distance from the nucleus of an atom. (The out-laying layers around an atom. An atom may have one, two or more of these.)

Answer 12

Electron shells

Question 13

Outer most Electron shell.

Answer 13

Valence shell

Question 14

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.

Answer 14

Chemical bonds

Question 15

A type of strong chemical bond in which TWO atoms share one or more pairs of VALence electrons.

Answer 15

Covalent bond

Question 16

Two or More atOms heLd together by covalent bonds.

Answer 16

Molecule

Question 17

The attraction of a given atom for the ELECtroNs of a covalEnt bond.

Answer 17

Electronegativity

Question 18

A 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.

Answer 18

Polar covalent bond

Question 19

A type of COVALENT BOND in which electrons are shared equally between two atoms of similar electronegativity.

Answer 19

Nonpolar covalent bond

Question 20

An atom or molecule with an electrical charge resulting from a gaIn Or loss of oNe or more electrons.

Answer 20

Ion

Question 21

A chemical BOND resulting from the attraction between oppositely charged atoms.

Answer 21

Ionic bond

Question 22

A compound resulting from the formation of an ionic bond. (Sodium chloride)

Answer 22

Salt

Question 23

A type of weak chemical BOND 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 (or in another region of the same molecule.)

Answer 23

Hydrogen bond

Question 24

A MOLECULE containing POLAR covalent bonds and having an unequal distribution of charges in different regions of the molecule.

Answer 24

Polar molecule

Question 25

The MAKING AND BREAKING of chemical bonds, leading to changes in the composition of matter.

Answer 25

Chemical reactions

Question 26

A starting material in a chemical REACTion.

Answer 26

Reactants

Question 27

The material resulting from the chemical reaction.

Answer 27

Product

Question 28

The tendency of molecules of the same kind to STICK together.

Answer 28

Cohesion

Question 29

The CLINGing of one substance to another.

Answer 29

Adhesion

Question 30

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

Answer 30

Surface tension

Question 31

The ENERGY associated with THE Random Movement of Atoms and moLecules.

Answer 31

Thermal energy

Question 32

Thermal energy in transfer from a warmer to a cooler body of matter.

Answer 32

Heat

Question 33

Measures the intensity of heat, that is, the average speed of molecules in a body of matter.

Answer 33

Temperature

Question 34

The process in which the surface of an object becomes cooler during EVAPORATION.

Answer 34

Evaporative cooling

Question 35

A liquid consisting of a uniform mixture of two or more substances

Answer 35

Solution

Question 36

The dissolving agent.

Answer 36

Solvent

Question 37

A substance that is dissolved. Eg : salt

Answer 37

Solute

Question 38

A solution in which water is the solvent.

Answer 38

Aqueous solution

Question 39

Best described as a MINGLING of molecules and/or ions.

Answer 39

Dissolving

Question 40

A substance that donates hydrogen (H+) ions to solutions.

Answer 40

Acid

Question 41

A substance that reduces the hydrogen (H+) ion concentration of a solution.

Answer 41

Base

Question 42

A measure of the 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+).]

Answer 42

pH scale

Question 43

Substance that minimize changes in pH.

Answer 43

Buffers

Question 44

Decreasing pH of ocean waters due to absorption of excess atmospheric CO2 from the burning of fossil fuels.

Answer 44

Ocean acidification

Question 45

A substance that cannot be broken down to other substances by ordinary chemical means.

Answer 45

Element