Chapter 2 - The Nature of Molecules Flashcards Preview

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Flashcards in Chapter 2 - The Nature of Molecules Deck (28):
1

atoms

Smallest element of a substance that retains the characters of the substance.

2

molecules

Groups of atoms, held by bonds

3

electrons

Negatively charged particles. Equals the number of protons in atoms.

4

protons

Positively charged particles in the center of an atom. Equals the number of protons in atoms.
(Determines the atomic number.)

5

neutrons

Neutral particles in the atom's nucleus.
(With the protons, determines the atomic weight/mass.)

6

ions

Charged atoms, that have gained or lost one or more electrons.
(Cations - positively charged, lost electron(s)
Anions - negatively charged, gained electron(s))

7

mass

Amount of a substance, a universal constant, independent of gravitational pull (weight)

8

Dalton

Discovered the fixed ratio of elements in substances (with the aid of electrolysis), such as H2O, CO2, etc.
(Worked with elements vs. compounds - a chemist, not an alchemist)

9

isotope

Atoms of the same elements that have different atomic masses due to differing numbers of neutrons.

10

oxidation

Loss of an electron
(Transferred to another atom while still retaining the energy level in the atom)

11

reduction

Gain of an electron

12

ionic bond

Formed by the attraction of oppositely charged ions

13

covalent bond

Formed when ions share 2 or more valence electrons
(Strength depends on the number of electron pairs shared by the atoms)

14

hydrogen bond

Weak attractions between the partially negative oxygen of one water molecule and the partially positive hydrogen of a different water molecule.
(Most important property of water.)

15

single bond

1 pair (2 electrons) shared between atoms in a covalent bond

16

double bond

2 pairs (4 electrons) shared between atoms in a covalent bond

17

polar

In covalent bonds, an unequal sharing of electrons

18

non-polar

In covalent bonds, an equal sharing of electrons

19

hydrophilic

"water loving"

20

hydrophobic

"water fearing"
(Water causes hydrophobic molecules aggregate or assume specific shapes.)

21

nucleus

The center of an atom, with protons and neutrons

22

orbital

Areas where electrons are found. Only 2 electrons per orbital. Those furthest from the nucleus have the greatest energy.

23

atomic number

Count of protons in an atom

24

atomic mass

Sum of protons and neutrons in an atom.

25

valence

Electrons in the outermost energy level of an atom.

26

pH

A measure of the amount of H+ ions in a substance

27

acid

Lower than 7 on the pH scale (greater concentration of H+ ions)

28

base

Higher than 7 on pH scale (lower concentrations of H+ ions)