Biology Chapter 2 The Chemical Context Of Life; Chapter 3 Water And Life

Front 1

Matter

Back 1

- Refers to anything that has mass and occupies space

- Exists in three states: Solid, liquid and gas

- Composed of basic substances called elements

Front 2

Element

Back 2

Substance that cannot be broken down into other substances with different properties; composed of one type of atom

92 are naturally occurring

Front 3

Carbon - Hydrogen - Nitrogen - Oxygen - Phosphorus - Sulfur

Back 3

The 6 elements that make up 96% of the body weight of organisms

Front 4

Atom

Back 4

- Smallest part of an element that displays the property of the element

- Shares the same name as its element

- Composed of subatomic particles: protons, neutrons and electrons

Front 5

Protons

Neutrons

Electrons

Back 5

- Contained in the central nucleus of an atom, positively charged, 1 amu, contains mass

- Contained in the central nucleus of an atom, no charge, 1 amu, contains mass

- Contained in the orbiting clouds around nucleus (electron shells), negatively charged, very low mass - negligible in calculations

Front 6

Atomic Number

Back 6

- Equal to the number of protons in each atom of an element

- Atoms are assumed to be electrically neutral so typically the number of electrons = number of protons

Front 7

Mass Number (Atomic Mass)

Back 7

Equal to the sum of the number of protons and neutrons in atom's nucleus

Front 8

Periodic Table (Dmitri Mendeleev)

Back 8

- Atoms of an element are arranged horizontally by increasing atomic number in rows called periods

- Atoms of an element arranged in vertical columns are called groups and share the same binding characteristics

- Atoms shown here are electrically neutral

Front 9

Groups (Periodic Table)

Back 9

Atoms within the same column on the periodic table share the same chemical binding characteristics

Example: Group VIII are noble gases and are inert

Front 10

Isotopes

Back 10

Atoms of the same element that differ in the number of neutrons and thus have different atomic masses

Some spontaneously decay (Radioactive rays or subatomic particles) and can be helpful or harmful

Front 11

Electrons

Back 11

- Attracted to the positively charged nucleus

- Takes energy to hold them in place and energy to push them away and keep them in their own shell

- The more distant the shell, the more energy it takes to hold in place

- Have energy due to their relative location (potential energy)

- Determine the chemical behavior of atoms

Front 12

Valence Shell

Back 12

- Outermost energy shell

- Determines many of an atom's chemical properties

- The number of electrons here determines whether the atom gives up, accepts or shares electrons to acquire 8 electrons in this outermost shell

Front 13

Molecule

Back 13

Two or more same elements bound together

Ex: H2, O2

Front 14

Compound

Back 14

Contains at least 2 different elements together

Ex: CO2, H2O, C6H12O6

Front 15

Formula

Back 15

Tells the number of each kind of atom in a molecule or compound

Front 16

Chemical Bonding

Back 16

- Bonds that exist between atoms in molecules and compounds contain energy

- These are the result of interactions between electrons in the outermost shell

- Atoms with incomplete valence shells can share or transfer valence electrons with certain other atoms

Front 17

Chemical Reaction

Back 17

Process of chemical bond formation

Front 18

Ion

Back 18

Atom that has lost or gained an electron

Front 19

Ionic Bond

Back 19

Forms when electrons are transferred from one atom to another atom and the oppositely charged ions are attracted to each other

Ex: Formation of NaCl

Front 20

Salts

Back 20

Solid substance that usually separate and exist as individual ions in water

Front 21

Covalent Bonds

Back 21

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

Front 22

Nonpolar covalent bond

Polar covalent bond

Back 22

- A covalent bond when electrons are shared equally between atoms

- A covalent bond when electrons are shared unequally

Front 23

Electronegativity

Back 23

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

Ex: O atom is more electronegative than H in H2O

Front 24

Hydrogen bond

Back 24

- Weak attraction between a slightly positive hydrogen atom and a slightly negative atom

- Can occur between atoms of different molecules or within the same molecule

- However collectively quite strong

- Helps to maintain proper structure and function of complex molecules such as proteins and DNA

Front 25

- High heat capacity (Aid in homeostasis)
- High heat of evaporation
- Good solvent (Because of polarity)
- Cohesive and Adhesive
- Solid state is less dense than liquid state (Expansion upon freezing)

Back 25

5 Properties of Water

Front 26

Hydrophilic/Hydrophobic Molecules

Back 26

Dissolve/ Do not Dissolve in Water

Front 27

Solution

Back 27

Contains dissolved substances or solutes

Front 28

Cohesion

Back 28

Ability of water molecules to cling to each other due to hydrogen bonding,

Ex: Water flows freely, surface tension, water transport in plants as well as transport in blood vessels

Front 29

Adhesion

Back 29

Ability of water molecules to cling to other polar surfaces because of its polarity

Example: Capillary action, water transport in plants as well as transport in blood vessels

Front 30

pH

Back 30

Measure of hydrogen ion concentration in a solution

Front 31

Acids

Back 31

Substances that dissociate in water, releasing hydrogen ions. High H+ concentrations

Front 32

Bases

Back 32

Substances that either take up hydrogen ions or release hydroxide ions. Low H+ concentration

Front 33

Buffer

Back 33

- Chemical or combination of chemicals that keeps pH within normal limits

- Minimize changes in concentrations of H+ and OH- in a solution

Front 34

Bohr Model

Back 34

Useful way to visualize electron location revolving around the nucleus in their energy shells (energy levels)

Front 35

- 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

Back 35

For atoms with atomic numbers of 20 or less, 3 rules apply

- These rules cover most of the biologically significant elements

Front 36

Octet Rule

Back 36

- States that the outermost shell is most chemically stable when it has 8 electrons except for when an atom has only one shell

- Tend to be chemically reactive if this is not met

Front 37

H2

O2

Methane

Back 37

3 Exmaples of nonpolar covalent bonds

Front 38

Water

Back 38

- Biological medium on Earth

- Only common substance to exist in the natural environment in all 3 physical states of matter

- Structure of its polar molecule allows it to interact with other molecules

- Unique emergent properties help make Earth suitable for life

Front 39

Evaporative cooling

Back 39

- The process where as liquid vaporizes, its remaining surface cools

Front 40

Ice

Back 40

- Less dense than liquid water

- Because hydrogen bonds between molecules become more rigid but also more open

- Acts as an insulator on top of cold water

Front 41

Acid

Neutral

Base

Back 41

pH Scale

1-6 describes?

7 describes?

8-14 describes?

Front 42

Acidosis

Alkalosis

Back 42

If blood pH drops below 7.0

If blood pH rises above 7.8

Front 43

7.4

Back 43

Normal pH of Human Blood