The Chemistry of Life

Question 1

what is an element?

Answer 1

a substance that cannot be broken down to other substances by chemical reactions

Question 2

what 4 elements make up 96% of living matter?

Answer 2

Carbon, hydrogen, oxygen, and nitrogen

Question 3

what is an atom?

Answer 3

the basic unit of a chemical element

Question 4

what is a subatomic particle?

Answer 4

a particle smaller than an atom

Question 5

what are the subatomic particles of an atom? what kind of charge do they have? what do they form/where are they found?

Answer 5

Protons
-positive charge
-form part of atomic nucleus in center of atom
Neutrons
-no electrical charge
-form part of the atomic nucleus in center of atom
Electrons
-negative charge
-form cloud around nucleus

Question 6

what is an electron shell? what determines how far a shell is located from the nucleus? can atoms have more than one shell? electrons in the outermost shell have more … than electrons in the innermost shell.

Answer 6

an electron shell is the orbit of a grouping of electrons around an atoms nucleus

• distance from nucleus is determined by the amount of energy the electron possesses
• atoms can have more than one shell as long as energy levels differ between electrons
• energy

Question 7

how many electrons can the innermost shell hold? how many can the 2nd and 3rd shells hold?

Answer 7

2 electrons = one pair

8 electrons = four pairs

Question 8

what determines the chemical properties of an atom?

Answer 8

-how many electrons are in its outermost shell

Question 9

what are electrons in the outer most shell are called?

Answer 9

valence electrons

Question 10

of the 5 main elements we talk about which ones have a high electronegativity? which ones have a low electronegativity?

Answer 10

high:
-oxygen
-nitrogen
low:
-carbon
-hydrogen
-phosphorus

Question 11

when/how will atoms interact with other atoms?

Answer 11

• atoms will interact with other atoms when they have unpaired electrons in their outermost shell
• they interact by sharing or transferring electrons

Question 12

what are chemical bonds?

Answer 12

are the interactions that atoms have by sharing/transferring electrons which usually result in atoms staying close together, held by attractions

Question 13

what are the 4 types of chemical bonds/interactions?

Answer 13

1. covalent bonds
2. hydrogen bond
3. ionic bond
4. hydrophobic interaction

Question 14

covalent bond:

1. how/when does it form?
2. is it strong or weak? how permanent is it?
3. how is represented in a drawing?

Answer 14

1. Formed when two atoms share pairs of electrons
2. Strong, relatively permanent bonds; requires large amount of energy to break
3. represented as a solid line between atoms

Question 15

what is a molecule?

Answer 15

two or more atoms held together by covalent bonds

Question 16

why do atoms share pairs of electrons?

Answer 16

to fill their outer orbital and become more stable

Question 17

are covalent bonds polar or non-polar? what determines this?

Answer 17

• covalent bonds can be either polar or non-polar

- Depends on the electronegativity of the two atoms sharing the pair of electrons

Question 18

what are non-polar covalent bonds?

Answer 18

-they are covalent bonds that form between atoms with same electronegativities, and therefore the atoms share electrons equally

Question 19

what are polar covalent bonds? what kind of charge does this result in?

Answer 19

-they are covalent bonds that form between atoms with different electronegativities, and therefore the atoms share electrons unequally.
-Unequal sharing of the electrons results in atoms
with partial positive and partial negative charges (in the same molecule)

Question 20

what is electronegativity? what element has the strongest electronegativity?

Answer 20

is a measure of how strongly specific atoms attract the electrons of a covalent bond to themselves
-oxygen (and the nitrogen)

Question 21

the more electronegative an atom is the more it … the shared electron …

Answer 21

pulls the shared electrons towards itself

Question 22

hydrogen bond:

1. how/when does it form?
2. is it strong or weak?
3. how is represented in a drawing?

Answer 22

1. Forms when a hydrogen atom, involved in a polar covalent bond, is attracted to a strongly electronegative atom such as oxygen or nitrogen
2. weak and non-permanent
3. dashed line

Question 23

what are polar and non-polar regions of a molecule? what kind of molecules do they occur in/why?

Answer 23

Polar regions
-contain atoms held together by polar covalent bonds
Nonpolar regions
-contain atoms held together by non-polar covalent bonds
-occur in molecules that are very large because they have many different kinds of bonds happening in them

Question 24

Ionic bond:

1. how/when does it form?
2. is it strong or weak? how permanent is it?
3. how is represented in a drawing?

Answer 24

1. formed when atoms strip electrons from their bonding
   partners, which causes the atom to become a charged ion, and the attraction between ions of opposite charge = ionic bond
2. not very strong/permanent; can be disrupted by water
3. dashed lines

Question 25

what is an ion?

Answer 25

an ion is a charged atom that has either lost or gained electron(s) -happens when atoms have unpaired electrons -eg. Na (sodium) atom has 1 electron in outer orbit Cl (chlorine) atom lacks 1 electron in outer orbit Cl takes electron from Na --> creates Na+ (sodium ion) and Cl- (chlorine ion) --> form an ionic bond with each other and become NaCl (sodium chloride)

Question 26

what is a hydrophilic substance? what will it do in water? what kinds of atoms/molecules are hydrophilic?

Answer 26

- a substance that has an affinity for water - will dissolve in water and form hydrogen bonds with water - ions, ionic compounds, polar molecules, or polar regions of molecules

Question 27

what is a hydrophobic substance? what will it do in water? what kinds of atoms/molecules are hydrophobic?

Answer 27

- a substance that does not have an affinity for water; repels water; held together by sharing of electrons - it will not dissolve in water or form bonds with water - non-polar molecules, or regions of molecules

Question 28

hydrophobic interaction: 1. how/when does it form? 2. is it strong or weak? how permanent is it? 3. how is represented in a drawing?

Answer 28

1. forms between non-polar molecules or non-polar regions of larger molecules; attraction of hydrophobic substances to one another in water, without bonding with water 2. Weak interactions that are non-permanent 3. dashed lines

Question 29

what is a functional group? what does it do/give to organic molecules? how do they attach?

Answer 29

- a biologically important chemical group - functional groups give organic molecules distinctive properties and are the components that are most commonly involved in chemical reactions - Attach to the carbon skeleton

Question 30

what are the seven functional groups that are most important in the chemistry of life?

Answer 30

1. Hydroxyl group 2. Carbonyl group 3. Carboxyl group 4. Amino group 5. Phosphate group 6. Methyl group 7. Sulfhydryl group

Question 31

hydroxyl: 1. what is the structure? 2. is it polar or non polar? 3. can it form hydrogen bonds? 4. is it hydrophilic or hydrophobic? 5. is it an acid or a base?

Answer 31

1. hydrogen atom bonded to an oxygen atom, which is bonded to the carbon skeleton of the organic molecule 2. polar 3. can form hydrogen bonds 4. hydrophilic 5. /

Question 32

Carbonyl: 1. what is the structure? 2. is it polar or non polar? 3. can it form hydrogen bonds? 4. is it hydrophilic or hydrophobic? 5. is it an acid or a base?

Answer 32

``` 1. oxygen atom double-bonded to a carbon atom 2. polar 3. can form hydrogen bonds 4. hydrophilic 5. source of H+ = acid ```

Question 33

Amino: 1. what is the structure? 2. is it polar or non polar? 3. can it form hydrogen bonds? 4. is it hydrophilic or hydrophobic? 5. is it an acid or a base?

Answer 33

``` 1. nitrogen atom bonded to 2 hydrogen atoms and the carbon skeleton 2. polar 3. can form hydrogen bonds 4. hydrophilic 5. can pick up H+ = base ```

Question 34

Carboxyl: 1. what is the structure? 2. is it polar or non polar? 3. can it form hydrogen bonds? 4. is it hydrophilic or hydrophobic? 5. is it an acid or a base?

Answer 34

1. oxygen atom double-bonded to a carbon atom that bonded to a hydroxyl group 2. polar 3. can form hydrogen bonds 4. hydrophilic 5. source of H+ = acid

Question 35

Phosphate: 1. what is the structure? 2. is it polar or non polar? 3. can it form hydrogen bonds? 4. is it hydrophilic or hydrophobic? 5. is it an acid or a base?

Answer 35

1. phosphorus atom bonded to 4 oxygen atoms, one oxygen is bonded to the carbon skeleton 2. polar 3. can form hydrogen bonds 4. hydrophilic

Question 36

Methyl: 1. what is the structure? 2. is it polar or non polar? 3. can it form hydrogen bonds? 4. is it hydrophilic or hydrophobic? 5. is it an acid or a base?

Answer 36

1. carbon atom bonded to 3 hydrogen atoms, which is bonded to the carbon skeleton of the organic molecule 2. nonpolar 3. / 4. hydrophobic 5. /

Question 37

Sulfhydryl: 1. what is the structure? 2. what are its functional properties?

Answer 37

1. hydrogen atom bonded to a sulfur atom, which is bonded to the carbon skeleton of the organic molecule 2. two sulfhydryl groups can react forming a covalent bond -covalent bond helps to stabilize protein structure

Question 38

what is the difference between single/double/triple covalent bonds?

Answer 38

- Single Bond: sharing of one pair of valence electrons - Double Bond: sharing of two pairs of valence electrons - Triple Bond: sharing of three pairs of valence electrons