Biology 12: Unit 1 Test

Front 1

Matter

Back 1

~ Anything that has mass and takes up space

~ Ex) Oxygen, Sodium Chloride

Front 2

Mass

Back 2

The measure of the amount of matter in a sample

Front 3

Volume

Back 3

The amount of space a sample of matter occupies

Front 4

Substance

Back 4

~ Matter with constant composition. All particles have the same properties.

~ Ex) Water, Helium

Front 5

Mixture

Back 5

~ Matter with variable composition. Made from two or more substances.

~ Ex) Soil, Sand

Front 6

Element

Back 6

~ A substance made up of atoms with the same atomic number

~ 92 naturally occurring elements

~ 25 of the 92 naturally occurring elements occur in living organisms

~ Of these 25, four elements make up ~96% of cytoplasm

- Oxygen: 65%, Carbon: 18.5%, Hydrogen: 9.5%, Nitrogen: 3.3%, Phosphorus: 1%, Sulphur: 0.3%

~ Ex) Lead, Sodium

~ All elements are made of identical atoms

Front 7

Compound

Back 7

~ A substance made from two or more elements, chemically combined.

~ Made up of units of atoms chemically bonded together. Consisting of individual units termed molecules or ions.

~ Ex) Carbon Dioxide

Front 8

Homogeneous Mixture

Back 8

~ A mixture made up of particles that are uniformly distributed.

~ Ex) Salt Water

Front 9

Heterogeneous Mixture

Back 9

~ A mixture made up of particles that are not uniformly distributed.

~ Ex) Raisin Bran

Front 10

Matter Vs. Substances

Back 10

~ Matter can be classified as substances or mixtures

~ Substances can be further classified as elements and compounds

Front 11

Elements Important To Life

Back 11

~ Calcium: 1.5%

~ Potassium: 0.4%

~ Sodium: 0.2%

~ Chlorine: 0.2%

~ Magnesium: 0.1%

~ Iron: 0.01%

~ Iodine: 0.01

Front 12

Atomic Structure: Atom

Back 12

~ The smallest unit of matter that retains the physical and chemical properties of the element

~ Consist of 3 subatomic particles

Front 13

Atomic Structure: Protons

Back 13

~ Mass: 1 amu, charge: +1

~ The number of protons determines the chemical properties of any atom

~ Protons are located within the nucleus of the atom

~ The number of protons can be determined from the element's atomic number

Front 14

Atomic Structure: Electrons

Back 14

~ Mass: negligible (0 amu), charge: -1

~ Electrons are located within energy level orbiting the nucleus of the atom

~ The number of electrons can also be determined from the element's atomic number. This is true because atoms are electrically neutral therefore the number of electrons equals the number of protons

Front 15

Atomic Structure: Neutrons

Back 15

~ Mass: 1 amu, charge: 0

~ Neutrons are located within the nucleus of the atom

~ The atomic mass is the combined total of an atom, the mass of the protons and the neutrons.

~ To determine the number of neutrons in any atom, subtract the atomic number from the atomic mass (i.e. number of neutrons = atomic mass - atomic number)

Front 16

Atomic Structure

Back 16

Any atom can vary in its normal number of electrons or neutrons but never in protons as a change in protons changes the identity of the element.

Front 17

Ions

Back 17

An atom which has gained or lost electrons, positively or negatively charged. Ions are highly reactive and are responsible for much of the chemistry of life.

Front 18

Isotope

Back 18

~ An atom with more or less than the typical number of neutrons. Many isotopes are unstable and eject subatomic particles from their nucleus at high speeds.

~ These are radioisotopes and are used for dating fossils, radioactive tracers used in medical diagnosis (thyroid or kidney disorder)

Front 19

Electron Configuration and Chemical Reactivity

Back 19

~ Electrons are moving around the atomic nucleus within a region of space termed energy levels or orbitals

~ It is the outermost level of electrons (i.e. valence electrons) that determines the reactivity of an atom

~ An element is most stable when its outermost electron shell is complete. Most of the elements important in biology have a maximum of 8 valence electrons

~ An element will react with another to achieve a complete e- configuration

Front 20

Ocelet Rule

Back 20

~ In chemical reactions, all atoms will react to achieve a stable ocelet configuration, 8 electrons in their outer energy level

~ To gain a stable e- configuration, atoms can

- gain electrons (reduction) eg. nonmentals

- lose electrons (oxidation) eg. metals

- share electrons eg. nonmentals

~ All chemical reactions involve energy as electrons must move between energy levels

Front 21

Types Of Chemical Bonds: Ionic Bonds

Back 21

~ Metals tend to have fewer valence electrons and will react to lose electrons to become stable; because they are losing electrons, a positive charge will result

~ Nonmetals tend to be missing electrons and will gain electrons to become stable; because they are gaining electrons, a negative charge will result

~ The positively and negatively charged particles result in ionic bonds. Individually they can be weak, but many can be collectively strong.

Front 22

Types Of Chemical Bonds: Properties Of Ionic Bonds

Back 22

~ Composed of a metal and a nonmetal (or polyatomic ion)

~ tend to form crystalline solids

~ tend to form lattice structures, which results in their tendency to form crystals and their strength in solid form

~ Polar in nature, and can readily dissolve in water to form solutions

~ when dissolved in water, they dissociate into free ions

~ high melting point in solid form

~ electrolytes: conduct a current of electricity when dissolved in solution

~ can be highly reactive

~ Ionic compounds can be divided into acids, bases and salts

Front 23

Types Of Chemical Bonds: Covalent Bonds

Back 23

~ A sharing of electrons is involved

~ Atoms in covalent compound complete their octet by sharing pairs of valence electrons, creating VERY strong bonds

~ The sharing of electrons between nonmetal atoms may be equal, resulting in a nonpolar covalent compound. They are hydrophobic and can be single, double or triple.

~The sharing of electrons between nonmetal atoms may be unequal, resulting in a polar covalent compound. They are hydrophilic.

- most polar covalent compounds involve oxygen or nitrogen (both are electronegative: strong ability to attract shared electrons in a covalent bond)

Front 24

Types Of Chemical Bonds: Properties Of Covalent Bonds

Back 24

~ Composed of two nonmetals

~ Tend to form gases (nonpolar covalent) and liquids (polar covalent)

~ Low melting point in solid form

~ Noneletrolytes: do not conduct a current of electricity when dissolved in a solution

Front 25

Types Of Chemical Bonds: Hydrogen Bonds

Back 25

~ A hydrogen bond is a polar chemical bond formed when the slightly positively hydrogen atom of a polar covalent compound is attracted to the slightly negative atom of a polar covalent bond in another molecule

~ Ex) Water forms hydrogen bonds with other water molecules

Front 26

Types Of Chemical Bonds: Van der Waal Interactions

Back 26

~ All molecules have areas of slight positive and negative charge, this is due to the uncertainty of electron position at any given point in time. As a result, all molecules attract each other.

~ These very weak and fleeting interactions are called Van der Waal interactions and they help hold matter together

Front 27

Types Of Chemical Reactions: Exothermic (Exergonic Reactions)

Back 27

~ Energy is released by the reaction

~ Reactants are at a higher level of potential energy than the products (-G)

Front 28

Types Of Chemical Reactions: Endothermic (Endergonic Reactions)

Back 28

~ Energy is absorbed by the reaction

~ Products contain more potential energy than the reactants (+G)

Front 29

Types Of Chemical Reactions: Exothermic and Endothermic (Exergonic & Endergonic Reactions)

Back 29

~ Before the reactions can occur, the natural repulsive forces of the reactants (due to electron clouds) must be overcome.

~ The energy that is used in the reaction to bring the reactants close enough together is called activation energy

~ In chemical reactions, this energy is typically hear which adds kinetic energy and increases the force of molecular collisions

~ In biology, heat cannot be used. The activation energy must be lowered using catalysts specifically biological ones called enzymes

Front 30

Chemical Compounds: Organic

Back 30

~ Contain both carbon and hydrogen atoms

~ Atoms are held together by covalent bonds

~ Compounds are often large, consisting of many atoms

~ Often associated with living things

~ Ex) Carbohydrates, Proteins, Fats (Lipids), Nucleic Acids (RNA & DNA)

Front 31

Chemical Compounds: Inorganic

Back 31

~ Lack either carbon and/or hydrogen atoms

~ Atoms are held together by ionic bonds

~ Compounds are small

~ Often associated with nonliving things

~ Ex) H20, NaCl, CO2

Front 32

Inorganic Compounds: Water

Back 32

~ Water is a polar compound; Electrons are shared between the oxygen and the two hydrogen atoms

~ Electrons are not shared equally and spend more time orbiting the oxygen nucleus resulting in the oxygen atom having a slightly negative charge and the hydrogen atoms having a slight positive charge

~ Waters polarity results in its ability to form hydrogen bonds

- Hydrogen bonds are weak which result from electrostatic attraction between the + hydrogen atoms and - oxygen atoms

- Hydrogen bonds form between neighboring molecules

Front 33

Properties Of Water: Cohesion

Back 33

~ Water is cohesive due to its polarity

- Water molecules stick together as they cover an organism's surface or move through tubular vessels (eg. plany xylem) This aids water's ability to keep organisms moist and to transport materials through multicellular organisms

- Cohesion between water molecules also creates the high surface tension of water, allowing some organisms to stand, run or walk without breaking the surface of water

Front 34

Properties Of Water: Specific Heat Capacity/ Heat Of Vaporization

Back 34

~ Water has a high specific heat capacity and high heat of vaporization

~ Important to living things because:

- It moderates earth's climate, reducing temperature extremes

- Allows large bodies of water to maintain a relatively constant temperature and support life

- Facilitates water's role as a temperature regulator as sweat evaporates, cooling the body

- Organisms consist of a lot of water, so are less affected by large temperature fluctuations

Front 35

Properties Of Water: Density Of Water

Back 35

~ Solids are generally more dense than liquids because there are more particles per unit volume

~ Water is more dense than ice due to hydrogen bonding. When water freezes, molecules organize themselves in a regular pattern, the hydrogen bonding prevents them from packing tightly together. This results in ice floating on top of water as it is more dense

Front 36

Properties Of Water: Solvent Properties

Back 36

~ Water is the universal solvent, it can dissolve all ionic substances as well as many covalent (polar) ones.

~ It dissolves ionic compound by surrounding the cation (+) and the anion (-) with its polar ends

~ Important:

- It allows chemical reactions to occur within cells. Most occur in aqueous solutions.

- It allows water to effectively transport dissolved substances through the body (i.e. dissolved in blood plasma - Mg+2, Ca+2, Na+1, CO2)

Front 37

Properties Of Water: State Of Water

Back 37

~ Water is a liquid at room temperature. Without the hydrogen bonds holding water molecules together, water would be a gas at room temperature.

~ Important:

- Liquid water is important in blood, lymph, cytoplasm

- Acts as a lubricant for our joints, facilitating their movement

Front 38

Acids, Bases and Buffers

Back 38

~ Occasionally a hydrogen atom participating in a hydrogen bond between two water molecules shifts from one water molecules to another

~ The polarity of water results in its ability to dissociate into ions (does not happen often)

- Ionization is written as H2O ------> H+ + OH-

~ In pure water only 1/10^7 water molecules are in the ionized state at any given moment (at 25)

~ This means that in a litre of pure water, there are on average 10^7 moles of water and 10^7 moles of hydroxide, if that equilibrium is upset it will become an acid or base

Front 39

The pH Scale

Back 39

~ 0-6: Acids

- Going down the line from 6-0, hydrogen increases while hydroxide decreases

~ 7: H20

~ 8-14: Bases

- Going up the line from 8-14, hydrogen decreases while hydroxide increases

Front 40

Acids

Back 40

~ pH < 7, proton donors

~ An acid is a strong compound which dissociates in water and releases hydrogen ions into solution

~ Acid strength increases as pH decreases

~ Acids increase the number of H+ ions in a solution

Front 41

Bases

Back 41

~ pH > 7, proton acceptors

~ A base is a compound which dissociates in water and often releases hydroxide ions into solution

~ Base strength increases as pH increases

~ Bases decrease the number of hydrogen ions in solution

Front 42

Buffers

Back 42

~ Compounds that resist changes in the pH of a solution

~ Most buffers are weak acids or bases that can shift their ionization equilibrium to maintain a constant H+

- When the H+ is too low ---> buffers take up H+

- When the H+ is too high ---> buffers release H+

~ Buffers can become overloaded

~Important:

- Hemoglobin (found in red blood cells) is important as a biological buffer as it helps living things maintain a constant pH (human blood is 7.4)

- In Biological systems, virtually all cell reactions occur in aq environments which are highly sensitive to very reactive hydrogen and hydroxide ions

Front 43

Cohesion

Back 43

The linking together of like molecules due to H bonds

Front 44

Adhesion

Back 44

The linking together of different molecules due to H bonds

Front 45

Specific Heat Capacity

Back 45

Quantity of energy required to change the temperature of a unit mass of a substance by 1 C

Front 46

Heat Of Vaporization

Back 46

The amount of energy required to change a substance from a liquid to a gas

Front 47

Why does water have a high heat capacity and high heat of vaporization?

Back 47

~ Because water is polar and has hydrogen bonds, the large number of hydrogen bonds result in water absorbing a lot of heat before evaporating and releasing a lot of heat before freezing

Front 48

Why the polarity of water is so important to organisms?

Back 48

1. Due to hydrogen bonding, water is a liquid at room temperature, allowing many organisms to use it for survival

2. Water is a universal solvent for polar molecules, facilitating chemical reactions both within and outside of the body

3. Due to its polarity, water is cohesive, allowing liquids to fill and interact with vessels like blood vessels

4. Due to the large number of hydrogen bonds, water has a high heat capacity and heat of vaporization allowing it to control temperature in large bodies of water

5. ^ keeps the body from overheating

Front 49

Why is water polar?

Back 49

A water molecule, because of its shape, is a polar molecule. That is, it has one side that is positively charged and one side that is negatively charged.

Front 50

How does the polarity of water molecules result in hydrogen bonding?

Back 50

Hydrogen bonding happens because a part of water molecule is negatively charged while another part is positively charged. The hydrogen part in a water molecule is attracted to the negatively charged part of another water molecule, while the oxygen part of water is attracted to the positively charged part of another water molecule.

Front 51

Polar

Back 51

When the electrons do not have an equal distribution of electrons in the orbit you have a polar molecule.

Front 52

Solvent

Back 52

A solvent is the solution, liquid, or gas part of the solute concentration.

Front 53

pH Scale

Back 53

A measure of acidity or alkalinity of water soluble substances

Front 54

Hydrogen Bonding

Back 54

A hydrogen bond is the electromagnetic attraction between polar molecules in which hydrogen is bound to a larger atom, such as oxygen or nitrogen. This is not a sharing of electrons, as in a covalentbond. Instead, this is an attraction between the positive and negative poles of charged atoms.