Ap Bio - Chapter 2

Front 1

Element

Back 1

A fundamental form of matter that has mass, takes up space, and cannot be broken down into something else on Earth.

Front 2

Atoms

Back 2

particles that retain the properties of an element.

Front 3

Protons

Back 3

Positive charge, one in every atom.

Front 4

Neutrons

Back 4

No charge, one in every atom.

Front 5

Nucleus

Back 5

Core of atoms; protons and neutrons

Front 6

Electrons

Back 6

Negative charge, normally equal amounts of electrons and protons.

Front 7

Atomic number

Back 7

Number of protons in each atom.

Front 8

Mass number

Back 8

Combined number of neutrons and protons.

Front 9

Isotopes

Back 9

Atoms that vary in neutron number.

Front 10

Radioisotope

Back 10

Isotope with unstable nucleus, stabilizes by emitting energy and particles.

Front 11

Radioactive decay

Back 11

Transforms a radioisotope into a new element.

Front 12

Tracers

Back 12

Substances with an isotope attached to them (often radioisotopes).

Front 13

Radiation therapy

Back 13

Radioisotopes stop activity of abnormal body cells.

Front 14

Orbital

Back 14

Space around nucleus in which electrons are likely to be found.

Front 15

Shell model

Back 15

A “shell” encloses all orbitals available to electrons at the same energy level.

Front 16

Inert atoms

Back 16

Atoms with no vacancies.

Front 17

Chemical bond

Back 17

Union between electron structures of atoms.

Front 18

Molecule

Back 18

Two or more bonded atoms.

Front 19

Diatomic molecules

Back 19

Molecules with two of the same element.

Front 20

Compounds

Back 20

Molecules with elements in proportions that never vary.

Front 21

Mixture

Back 21

Two or more elements or compounds intermingled in proportions that usually vary.

Front 22

Ionic bond

Back 22

Association of two ions with opposing charges.

Front 23

Ion

Back 23

Atom that has either lost or received an electron (charged).

Front 24

Covalent bond

Back 24

sharing of a pair of electrons between two atoms.

Front 25

Non-polar covalent bond

Back 25

No difference in change between ends of bond, atoms share electrons equally.

Front 26

Polar covalent bond

Back 26

More attractive (electronegative atom) exerts stronger pull on electrons --> slightly negative (No molecular net charge).

Front 27

Hydrogen bond

Back 27

Weak attraction between an electronegative atom and a hydrogen atom taking part in a second polar covalent bond.

Front 28

Hydrophilic substances

Back 28

Polar substances, attracted to water.

Front 29

Hydrophobic substances

Back 29

Non-polar molecules, repel hydrophilic substances and water.

Front 30

Temperature

Back 30

Measure of molecular motion.

Front 31

Cohesion

Back 31

Capacity to resist rupturing when placed under tension.

Front 32

“Spheres of Hydration”

Back 32

Formed when water molecules cluster around oppositely charged solute (dissolved substances) ions or molecules

Front 33

pH scale

Back 33

Determines H+ concentration in liquids.

Front 34

Neutrality

Back 34

pH = 7, pure water, [H=] = [OH-]

Front 35

Acids

Back 35

pH = 0-7, proton donators (lemon juice, coffee)

Front 36

Bases

Back 36

pH = 7-14, proton acceptors (seawater, baking soda, “alkaline” fluids).

Front 37

Salts

Back 37

Compounds that release ions other than H= and OH- in solutions.