Bio Chapter 2

Front 1

element

Back 1

substances that cannot be broken down into simpler substances by ordinary chemical reactions

Front 2

oxygen

Back 2

O

Front 3

carbon

Back 3

C

Front 4

hydrogen

Back 4

H

Front 5

nitrogen

Back 5

N

Front 6

calcium

Back 6

Ca

Front 7

Phosphorus

Back 7

P

Front 8

potassium

Back 8

K

Front 9

Sulfur

Back 9

S

Front 10

sodium

Back 10

Na

Front 11

magnesium

Back 11

Mg

Front 12

Chlorine

Back 12

Cl

Front 13

iron

Back 13

Fe

Front 14

matter

Back 14

anything that has mass and takes up space

-components of atoms
-dont work with chemical properties

Front 15

electron

Back 15

a particle that carries a unit of negative charge

Front 16

proton

Back 16

a particle that carries a unit of positive charge

Front 17

neutron

Back 17

an uncharged particle

Front 18

atomic nucleus

Back 18

composed of protons and neutrons

-electrons exist outside of this

Front 19

atomic number

Back 19

the fixed number of protons in an elements atomic nucleus

Front 20

atomic mass unit (amu)

Back 20

unit of measure for the mass of subatomic particles

1 x = 1 proton or 1 neutron
1/1800 x = 1 electron

Front 21

atomic mass

Back 21

a number that indicates how much matter an atom of an element contains

*left postscript

Front 22

isotopes

Back 22

atoms which consist of a mixture of atoms with different numbers of neutrons and therefore have different masses

-of the same element have the same numbers of protons and electrons, on the number of neutrons varies

ex: carbon 14 is a _____ of carbon?

Front 23

radioisotopes

Back 23

isotopes which are unstable and tend to break down or decay to a more stable isotope, usually becoming a different element

-emit radiation as they decay

Front 24

autoradiography

Back 24

a way of detecting radioactive decay in which radiation causes the appearance of dark silver grains in photographic film

Front 25

orbitals

Back 25

3d space in which electrons move

-each of these contains a maximum of 2 electrons

-these are depicted as electron clouds because it is impossible to know where an electron will be at any moment

-energy of an electron depends on which one of these it occupies

Front 26

electron shell

Back 26

electrons in orbitals with similar energies

-greater distance from the nucleus = greater energy

-smaller distance from the nucleus = smaller energy

Front 27

valence electrons

Back 27

the most energetic electrons that occupy the outermost orbital

Front 28

valence shell

Back 28

the outermost concentric ring in a bohr model

-houses the most energetic electrons

-the play a key role in chemical reactions

-electrons can move to different orbitals by gaining or losing electrons

Front 29

the chemical behavior of an atom is determined primarily by the number and arrangement of its valence electrons

-valence shell of H or He is full with 2 electrons, any other atom is full with 8 electrons

-when the valence shell is not full the atom tends to gain, lose, or share electrons to achieve a full valence shell

- the valence shells of all isotopes of an element are identical, in this way they have similar chemical properties and can be substituted for one another in chemical reactions

Back 29

info on valence electrons:

Front 30

chemical compound

Back 30

consists of atoms of 2 or more different elements combined in a fixed ratio

Front 31

molecular mass

Back 31

this is found by determining the sum of the atomic masses of the component atoms of a single molecule

-measured in amu or grams

Front 32

mole (mol)

Back 32

the amount of an element or compound whose mass in grams is equivalent to its atomic or molecular mass

Front 33

6.022 x 10^23

- the number of units in 1 mol

Back 33

what is avogadros number?

Front 34

dynamic equilibrium

Back 34

when the rates of forward and reverse reactions are equal

Front 35

bond energy

Back 35

the energy necessary to break a chemical bond

-valence electrons dictate how many bonds an atom can form

Front 36

covalent bonds

Back 36

involve the sharing of electrons between atoms in a way that results in each atom having a filled valence shell

Front 37

covalent compound

Back 37

unlike atoms linked by covalent bonds to form molecules

Front 38

single covalent bond

Back 38

when one pair of electrons is shared between 2 atoms

Front 39

double covalent bond

Back 39

when 2 pairs of electrons are shared between 2 atoms

- in molecular oxygen, 2 O atoms share 2 pairs of electrons, forming this

Front 40

orbital hybridization

Back 40

when an atom forms covalent bonds with other atoms, the orbitals in the valence shells may become rearranged, thereby affecting the shape of the molecule...what this process called?

Front 41

electronegativity

Back 41

a measure of an atoms attraction for shared electrons in chemical bonds

Front 42

nonpolar covalent bond

Back 42

when covalently bonded atoms have similar electronegativities and the electrons are shared equally

Front 43

polar covalent bonds

Back 43

a covalent bond between atoms that differ in electronegativity

-such a bond has 2 dissimilar ends, one with a partial positive charge and the other with a partial negative charge

Front 44

ion

Back 44

a particle with one or more units of electrical charge

- an atom becomes this if it gains or loses one of more electrons

- an atom with 1, 2, or 3 electrons in its valence shell has a tendency to lose electrons to other atoms. such an atom then becomes positively charged because its nucleus has more protons than the electron cloud posses in electrons

Front 45

cations

Back 45

positively charged ions

Front 46

anions

Back 46

negatively charged ions

Front 47

ionic bond

Back 47

forms as a consequence of the attraction between the positive charge of a cation and the negative charge of an anion

Front 48

ionic compound

Back 48

a substance consisting of anions and cations bonded by their opposing charges

-compounds joined by ionic bonds have a tendency to separate into their individual ions when placed in water

-in solid form, very strong

Front 49

solvent

Back 49

as a liquid, ti is capable of dissolving many substances, particularly those that are polar or ionic

Front 50

solute

Back 50

a dissolved substance

Front 51

hydration

Back 51

in solution, when each cation and anion of the ionic compound is surrounded by oppositely charged ends of the water molecules

Front 52

hydrogen bond

Back 52

when H combines with O or with another relatively electronegative atom, it acquires a partial positive charge because its electron spends more time closer to the electronegative atom

-these bonds tend to form between an atom with a partial negative charge and a H atom that is covalently bonded to O or N

-these bonds are readily formed and broken

-although individually weak, these bonds are collectively strong when present in large numbers

Front 53

van der waal interactions

Back 53

the attractive forces, that operate over very short distances and are weaker and less specific that covalent bonds or ionic bonds

-they are most important when they occur in large numbers and when they can permit close conduct between atoms

-ind. weak, collectively strong

Front 54

oxidation

Back 54

a chemical process in which an atom, ion, or molecule loses electrons

-always occurs with reduction

Front 55

reduction

Back 55

a chemical process in which an atom, ion or molecule gains electrons

-always occurs with oxidation

Front 56

cohesion

Back 56

the ability to stick to one another

-helps water molecules stick together and move together

Front 57

adhesion

Back 57

the ability to stick to many other kinds of substances

Front 58

capillary action

Back 58

a combination of adhesive and cohesive forces

-this is a tendency of water to move in narrow tubes, even against the force of gravity

Front 59

surface tension

Back 59

cohesion of its molecules, which have a much greater attraction for another than for molecules in the air

-water molecules are polar, one end of each molecule bears a partial positive charge and the other a partial negative charge

Front 60

hydrophilic

Back 60

water-loving, substances that interact readily with water

Front 61

hydrophobic

Back 61

water-fearing, substances that dont readily interact with water

Front 62

hydrophobic reactions

Back 62

occur between groups of nonpolar molecules. such molecules are insoluble in water and tend to cluster together

Front 63

kinetic energy

Back 63

the energy of motion

Front 64

heat

Back 64

refers to the total amount of kinetic energy in a sample of a substance

Front 65

temperature

Back 65

a measure of the average kinetic energy of the particles in a substance

Front 66

heat of vaporization

Back 66

the amount of heat energy required to change 1g of a substance from the liquid phase to the vapor phase, expressed in the unit of calories

Front 67

calorie

Back 67

the amount of heat energy required to raise the temperature of 1g of water to 1*C

Front 68

evaporative cooling

Back 68

when faster moving molecules escape the liquid phase and move to the vapor, taking heat with them in the process

Front 69

ionize

Back 69

tendency in water molecules to dissociate into H ions (H+) and hydroxide ions (OH-)

Front 70

acid

Back 70

a substance that dissociates in solution to yield H ions (H+) and anions

Front 71

base

Back 71

substance that dissociates to yield hydroxide ions (OH-) and a cation when dissolved in water

Front 72

pH

Back 72

Defined as the negative logarithm of the H ion concentration

Front 73

neutral solution

Back 73

pH = 7, has equal concentrations of H ions and hydroxide ions

Front 74

acidic solution

Back 74

pH - less than 7, has more H+ than OH- ions

Front 75

basic solution

Back 75

pH = greater than 7, has more OH- than H+ ions

Front 76

buffer

Back 76

a substance or combination of substances that resists change in pH when an acid or base is added

Front 77

dynamic equilibrium

Back 77

when the ratio of the forward and reverse reactions are equal and the relative concentrations of the components are not changing

-the equilibrium can be shifted and a subsequent new one is formed if outside stress is placed on the system

Front 78

salt

Back 78

a compound in which the H ion of an acid is replaced by some other cation

Front 79

electrolytes

Back 79

when a salt, acid, or base is dissolved in water, it dissociated ions can conduct electric current, these ions are called what?

Front 80

non-electrolytes

Back 80

other substances that are dissolved in water and do not form ions and dont conduct electric current