Biology Chapter 2

Front 1

Matter

Back 1

anything that has mass and occupies space

Front 2

what states does matter exist in

Back 2

solid, liquid, and gas

Front 3

all matter is composed of what

Back 3

elements

Front 4

an element

Back 4

a substance that cannot be broken down into substances with different properties; composed fo one type of atom

Front 5

What six elements make up 95% of the body weight of organisms

Back 5

carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur (CHNOPS)

Front 6

an atom

Back 6

is the smallest part of an element that displays the property of the element. an element and its atom share the same name.

Front 7

an atom is composed of

Back 7

subatomic particles: protons, neutrons, electrons

Front 8

what is in the central nucleus

Back 8

protons positivly charged, neutrons no charge

Front 9

in orbiting clouds around the nucleus

Back 9

electrons - negatively charged, very low mass-negligible in calculations

Front 10

each element is represented by

Back 10

one or two letters to give it a unique atomic symbol

Front 11

the atomic number

Back 11

is equal to the number of protons in each atom of an element

Front 12

the mass number of an atom

Back 12

is equal to the sum of the number of protons and neutrons in an atom's nucleus

Front 13

the atomic mass is approximately equal

Back 13

to the mass number

Front 14

atoms of an element are arranged

Back 14

horizontally by increasing atomic number in rows called periods

Front 15

atoms of an element arranged in vertical columns are call

Back 15

groups

Front 16

atoms within the same group share the same

Back 16

binding characteristics

Front 17

atoms shown in the periodic table are electrically

Back 17

neutral

Front 18

therefor the atomic number tells you the number of

Back 18

electrons as well as the number of protons

Front 19

isotopes are

Back 19

atoms of the same element that differ in the number of neutrons ( and therefore different atomic masses)

Front 20

some isotopes

Back 20

spontaneously decay

Front 21

radioactive isotopes

Back 21

give off energy in the form of rays and subatomic particles

Front 22

Isotopes can be helpful or harmful

Front 23

electrons are attracted

Back 23

to positively the charged nucleus, thus it takes energy to hold electrons in place

Front 24

what does it take to push electrons away and keep them in their own shell

Back 24

energy

Front 25

the more distant the shell

Back 25

the more energy it takes to hold in place

Front 26

electrons have energy due to

Back 26

their relative position (potential energy)

Front 27

electrons determine

Back 27

chemical behavior of atoms

Front 28

electrons revolve around the nucleus

Back 28

in energy shells (energy levels)

Front 29

for atoms with atomic numbers of 20 or less, the following rules apply

Back 29

the first energy shell can hold up to 2 electrons, each additional shell can hold up to 8 electrons, each lower shell is filled first before electrons are placed in the next shell

Front 30

the outermost energy shell is called the

Back 30

valence shell

Front 31

the valence shell is important because it

Back 31

determines many of an atom's chemical properties

Front 32

what rule states the the outermost shell is most stable when it has eight electrons

Back 32

the octet rule

Front 33

what is the exception of the octet rule

Back 33

if an atom has only one shell the outermost valence shell is complete when it has two electrons

Front 34

the number of electrons in an atom's valence shell determines

Back 34

whether the atom gives up, accepts, or shares electrons to acquire eight electrons in the outer shell

Front 35

atoms that have their valence shells filled with electrons tend to be

Back 35

chemically stable

Front 36

atoms that do not have their valence shells filled with electrons are

Back 36

chemically reactive

Front 37

a molecule

Back 37

is two or more elements bonded together

Front 38

a compound

Back 38

is a molecule containing at least two different elements bonded together

Front 39

a formula

Back 39

tells you the number of each kind of atom in a molecule

Front 40

bonds that exist between atoms in molecules contain

Back 40

energy

Front 41

bonds between atoms are caused by

Back 41

the interactions between electrons in outermost energy shells

Front 42

the process of bond formation is called a

Back 42

chemical reaction

Front 43

an atom that has lost or gained an electron

Back 43

ion

Front 44

forms when electrons are transferred from one atom to another atom and the oppositely charged ions are attracted to one

Back 44

ionic bond

Front 45

what is an example of an ionic bond

Back 45

formation of sodium chloride

Front 46

solid substances that usually separate and exist as individual ions in water

Back 46

salts

Front 47

These result when two atoms share electrons so each atom has an octet of elections in the outer shell

Back 47

covalent bonds

Front 48

in the case of hydrogen the outer energy shell is complete when it contains

Back 48

2 electrons

Front 49

in this, electrons are shared equally between atoms

Back 49

nonpolar covalent bonds

Front 50

what are some examples of nonpolar covalent bonds

Back 50

hydrogen gas, oxygen gas, methane

Front 51

in this electrons are share unequally

Back 51

polar covalent bonds

Front 52

an example of a polar covalent bond

Back 52

water

Front 53

the ability of an atom to attract electrons towards itself in a chemical bond

Back 53

electronegativity, in water the oxygen atom is more electronegative than the hydrogen atoms and the bonds are polar

Front 54

water is

Back 54

a polar molecule

Front 55

the shape of a water molecule and its polarity

Back 55

make hydrogen bonding possible

Front 56

a weak attraction between a slightly positive hydrogen atom and a slightly negative atom

Back 56

a hydrogen bond

Front 57

a hydrogen can occur

Back 57

between atoms of different molecules or within the same molecule

Front 58

hydrogen bombs help to maintain

Back 58

the proper structure and function of complex molecules such as proteins and DNA

Front 59

water molecules cling together because of

Back 59

hydrogen bonding

Front 60

the presence of many hydrogen bonds allow water to

Back 60

absorb a large amount of thermal heat without a great change in temperature

Front 61

the temp of water

Back 61

rises and falls slowly it allows organisms to maintain internal temperatures

Front 62

hydro bonds must be broken to

Back 62

evaporate water

Front 63

bodies of organisms cool

Back 63

when their heat is used to evaporate water

Front 64

why is water a good solvent

Back 64

because of its polarity, polar substances dissolve readily in water, hydrophilic molecules dissolve in water, hydrophobic molecules do not dissolve in water

Front 65

the ability of water molecules to cling to each other due to hydrogen bonding

Back 65

cohesion

Front 66

the ability of water molecules to cling to other polar surfaces

Back 66

adhesion

Front 67

adhesion is due to

Back 67

water's polarity

Front 68

cohesion and adhesion account for

Back 68

water transport in plants as well as transport in blood vessels