Chapter 2

Question 1

How do covalent bonding hold molecules together?

Answer 1

Both atoms are trying to attract same electrons. Force of attraction that each atom exerts on the shared electrons is what holds the two atoms together

Question 2

(Define) Element’s mass number

Answer 2

Total number of protons and neutrons in an atomic nucleus

Question 3

(Define) Atomic number

Answer 3

The number of protons in the nucleus of an atom, which determines the chemical properties of an element and place in the periodic table.

Question 4

Why is carbon important?

Answer 4

Key component for all life (to live, grow, and reproduce). Main element in organic compound. Has 4 valence electrons

Question 5

Water properties:

Answer 5

1. Cohesion/adhesion
2. surface tension
3. Water denser as a liquid than a solid
4. high capacity for absorbing energy

Question 6

What makes water a great solvent?

Answer 6

Because it is capable of dissolving a variety of different substances. [Polar, owing partial H:positive charge & O:negative]

Question 7

What determines if a reaction is spontaneous?

Answer 7

1. When the product molecules are less ordered than the reactant molecules.
2. If the product have lower potential energy than the reactants.
   [chemical reactions are spontaneous if they are able to proceed on their own without added energy]

Question 8

What determines if the reaction is exothermic?

Answer 8

“Outside heating” releases heat (gas to liquid)

Question 9

What determines if a reaction is endothermic?

Answer 9

“Within heating”. Heat is absorbed during the process (liquid to gas)

Question 10

(Define) Energy:

Answer 10

The capacity to do work or to supply heat

Question 11

(Define) potential energy:

Answer 11

Stored energy [called chemical energy, when stored in chemical bonds]

Question 12

(Define) kinetic energy:

Answer 12

Energy of motion [called thermal energy in molecular motion]

Question 13

(Define) hydrophobic:

Answer 13

Substances that do not interact w/water [water fearing]

Question 14

(Define) hydrophilic:

Answer 14

Substances that interact w/water (water loving)

Question 15

Stanley Miller Experiment:

Answer 15

• hypoth. that life originated from basic molecules from early earth
• idea that gases from atmosphere and sea were stimulated by lighting to produce chemicals for organisms

Question 16

(Define) functional groups:

Answer 16

Particular spatial arrangements of atoms that have predictable chemistry [how they are going to behave]

Question 17

Amino and Carboxyl functional groups:

Answer 17

Animo groups function as bases; Carboxyl groups act as acids. Tend to attract/drop a proton, when in solution

Question 18

Phosphate groups:

Answer 18

Carry two negative charges

Question 19

Sulfhydryl groups:

Answer 19

Consists of a sulfur atom bonded to a hydrogen atom

Question 20

Atomic structure:

Answer 20

• sm particles(electrons) orbit an atomic nucleus.

- nucleus: protons & neutrons

Question 21

(Define) isotopes:

Answer 21

Forms of an element w/different numbers of neutrons

Question 22

Bonding in terms of valence shell electrons:

Answer 22

The outermost shell of an atom, where unpaired electrons move around, and overlap between two atomic orbitals

Question 23

(Define) electronegativity:

Answer 23

The ability of an atom to attract shared electrons (how much electrons want to be around that element)

Question 24

(Define) polar covalent bond:

Answer 24

• A bond in which the two atoms have different electronegativities, causing a separation of charges.
• are asymmetrical
• other elements want to be around it

Question 25

(Define) non polar covalent bond:

Answer 25

- In which two atoms have identical or very similar electronegativities, so that the charges are distributed evenly. - symmetrical

Question 26

(Define) ionic bond:

Answer 26

- a complete transfer of valence electrons between atoms. - a type of bond that generates two oppositely charges ions - metals to non metals