Biology Chapter 2 103 Rvc

Front 1

Matter

Back 1

anything that takes up space and has mass

Front 2

element

Back 2

cannot be broken down into another substance

Front 3

Human make up six elements 98%

Back 3

Oxygen 65%
Carbon 18%
Hydrogen 10%
Nitrogen 5%
Phosphorus 1,1%
Sulfur and others 0.9%

Front 4

Elements have properties---properties are

Back 4

physical or chemical characteristics, such as density, solubility, melting point, and reactivity

Front 5

Atomic Theory

Back 5

All elements are made up of tiny particles called atoms

Front 6

Atoms are made up of

Back 6

Neutrons- neutral charges
Protons - positive charges
Electrons negative charges

Front 7

Protons and neutrons are located in the center of the atom called

Back 7

the nucleus

Front 8

Atomic mass

Back 8

is the combined weight of the neutrons and protons of the atom

Front 9

Atomic number

Back 9

is the number of protons in the element

Front 10

Isotopes

Back 10

are atoms of an element that differ in amount of nuetrons

Front 11

Tracer

Back 11

is a radioactive isotope that can be used to detect molecular changes inside the body

Front 12

Food irradiation

Back 12

can be used to kill harmful bacteria and not damage (cause the food to become radioactive) food

Front 13

Electrons in outer levels

Back 13

contain more energy then those closer

Front 14

Electron shells

Back 14

first shell contains 2 electrons
second shell contains 8
third shell contains 18 and the fourth 32

Front 15

Octet rule

Back 15

the outer shell is most stable when it holds 8 electrons

Front 16

Valence Shell

Back 16

is the outermost shell of the ataom

Front 17

Molecule

Back 17

is a group of atoms bonded together

Front 18

Compound

Back 18

a molecule that contains atoms of more then one element

Front 19

Ionic Bonding

Back 19

forms from the attraction of two atoms held together by opposite charges

Front 20

The transfer of electrons between atoms are called an

Back 20

ions

Front 21

Covalent Bonding

Back 21

results from two atoms share electrons in order to have a complete outer shell

Front 22

photosynthesis enables plants to make molecules

Back 22

6 CO2 +6 H2O = C6H12O6 + 6O2
Plants take 6CO2 +6H2O and make glucose C6H12O6 and 6O2 oxygen

Front 23

reactants

Back 23

molecules that participate in the reaction
In Photosynthesis
6CO2 + 6 H2O Carbon Dioxide and Water

Front 24

products

Back 24

molecules formed by the reaction
C6H12O6 + 6O2
Glucose and oxygen

Front 25

Water

Back 25

is the single most important molecule on Earth

Front 26

Electronegativity

Back 26

The electronegativity is related to its size of the atom in a covalent bond smaller have less electronegativity then larger atoms

Front 27

Atoms with more electronegativity tend to hold shared electrons more tightly this is called

Back 27

Polar meaning that atoms on both sides of the bond become partially charged

Front 28

The Positive charge in hydrogen atoms are attracted to the negative charge of oxygen atoms in other molecules this is called

Back 28

hydrogen (H) bond

Front 29

Water is a solvent

Back 29

because of its polarity and h-bonding ability water dissolves a great number of substances

Front 30

Molecules that are attracted to water are called

Back 30

Hydrophilic---normally Polar and ionized molecules

Front 31

Hydrophobic

Back 31

Molecules that are not attracted to water---such as nonionzed and nonpolar molecules

Front 32

NaCl

Back 32

dissolves in water the Na is attracted to the oxygen ends of the water while the Cl is attracted to the Hydrogen ends water dissolves many polar and non-ionic substances

Front 33

Cohesion

Back 33

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

Front 34

Adhesion

Back 34

refers to the ability of water molecules to cling to other polar surfaces

Front 35

Water has a high surface tension

Back 35

Water molecules st the surface are more strongly attracted to each other than to the air above

Front 36

Water has a high heat capacity

Back 36

it allows water to heat slowly and also to cool slowly

Front 37

Water is less dense then ice

Back 37

water expands as it freezes Ice protects lakes and other water bodies from freezing solid

Front 38

Acidic solutions

Back 38

have a sharp sour taste

Front 39

Acids

Back 39

are important to chemists because they dissociate in water releasing hydrogen ions

Front 40

The acidity of a substance

Back 40

depends on how fully it dissociates in water HCl in water dissociates almost completely

Front 41

Base solutions have a

Back 41

bitter taste

Front 42

Bases are substance that

Back 42

either take up hydrogen ions or release hydroxides

Front 43

NaOH is an import base

Back 43

it breaks up as Na- + OH- like an acid a base's strength is measured by how fully it dissociates

Front 44

pH

Back 44

is a mathematical way of indicating the number of hydrogen ions in a solution

Front 45

pH Scale

Back 45

ranges from 0 to 14 0to6 is acidic 7 is neutral Hydrogen ions and Hydroxide ions are equal 8 to 14 are base each number represents 10 times the previous

Front 46

A Buffer

Back 46

is a chemical or a combination of chemicals that keep pH with in normal limits in the human body