Principles Of Biology - Chapter 2

Front 1

Diagram or describe the basic composition of an atom.

Back 1

Both neutrons and protons are in the nucleus of the atom; electrons orbit the nucleus in electron shells/orbitals.

Front 2

List the 3 main subatomic particles, noting their location and charges:

Back 2

1. Proton - Nucleus; positive; mass of 1; determines element

2. Neutron - Nucleus; neutral; mass of 1; determines isotope

3. Electron - Orbits nucleus in electron shells/orbitals; negative; negligible mass; determines chemical reactivity and ionic state

Front 3

The atomic number is the number of_________

Back 3

protons

Front 4

The atomic mass is the number of__________and____________

Back 4

protons, neutrons

Front 5

Isotopes are forms of an element with different numbers of_______________

Back 5

neutrons

Front 6

The number of____________determines how atoms will interact.

Back 6

electrons

Front 7

Define element.

Back 7

A pure substance containing only one kind of atom.

Front 8

Note how many electrons are in each electron shell:

1) First shell

2) Second shell

3) Third shell

Back 8

1) One s orbital holds 2 electrons

2) 1 s orbital and 3 p orbitals (holds 8 electrons)

3) 4 orbitals (8 electrons each)

Front 9

Draw the electron configuration of Carbon:

Back 9

6+ electrons total; first orbital holds 2, second orbital holds 4, can consequently make 4 bonds.

Front 10

_______________________determines how the atom behaves.

Back 10

Outermost electron shell (valance shell)

Front 11

Define covalent bond.

Back 11

Atoms share one or more pairs of electrons, so that the outer shells are filled.

Front 12

Define electronegativity.

Back 12

The attractive force that an atomic nucleus exerts on electrons.

Front 13

Define polar covalent bond and give an example molecule.

Back 13

Results when electrons are drawn to one nucleus more than to the other, because one atom has more electronegativity. Because of this unequal sharing, the bond has a slight negative charge on one end and a slight positive charge on the other. An example of a polar covalent bond is water.

Front 14

Nonpolar covalent bond and example.

Back 14

When one atom is much more electronegative than the other, a complete transfer of electrons may occur. This results in two ions with fully paired electrons in their outer shells. An example is methane.

Front 15

Ionic bond and example.

Back 15

When one atom is much more electronegative than the other, a complete transfer of electrons may occur. This results in two ions with fully paired electrons in their outer shells. A cation is positive, an anion is negative. An example of an ionic bond is sodium chloride.

Front 16

Hydrogen bond and example.

Back 16

Attraction between the delta-negative end of one molecule and the delta-positive hydrogen end of another molecule. Hydrogen bonds form between water molecules and are important in the structure of DNA and proteins.

Front 17

Define the following: 1) Hydrophilic, 2) Hydrophobic

Back 17

1) Water-loving; polar molecules forming hydrogen bonds with water

2) Water-hating; nonpolar molecules like hydrocarbons that interact with each other but not water

Front 18

Water has unique structure and special properties:

Back 18

1) Polar molecule

2) Forms hydrogen bonds

3) Tetrahedral shape

Front 19

Because of these, water is able to support life. How? List specific examples.

Back 19

1) Ice floats, saving life below water.

2) Specific heat regulates the climate temperature of Earth.

3) Heat of vaporization or evaporative cooling allows humans to cool themselves through sweating.

4) Cohesion helps water move through plants and enables humans to float will swimming.

Front 20

A solution is a substance________dissolved in a liquid_________

Back 20

solute, solvent

Front 21

Define the following and give their range on the pH scale. 1) Acids, 2) Bases

Back 21

1) Acids dissolve in water and release hydrogen ions (H+ protons); from 1-7 on the scale

2) Accept H+ ions; from 7-14 on the scale

Front 22

What do Buffers do?

Back 22

They help maintain constant pH. A buffer is a weak acid and its corresponding base.

Front 23

Define van der Waals forces.

Back 23

Attractions between nonpolar molecules that are close together -- individual interactions are brief and weak, but summed over a large molecule can be substantial.