Biochemistry 1 (1)

Question 1

What is a protein?

Answer 1

A polymer of amino acids that folds into a particular shape

Question 2

Describe the nucleus

Answer 2

-made up of protons and neutrons
-number of protons=number of electrons
-atom is neutral

Question 3

Where are electrons found in the atomic structure?

Answer 3

-found in energy levels orbiting the nucleus
-levels divided into atomic orbitals

Question 4

What are atomic orbitals?

Answer 4

Particular regions of space within which electrons mostly reside

Question 5

What are the shapes of S and P orbitals?

Answer 5

s - spherical
p (made up of x,y,z) - dumbbell

Question 6

What is a node?

Answer 6

Space between 1s and 2s atomic orbitals where electrons won’t reside

Question 7

What is the nodal plane?

Answer 7

Space between 2p lobes where you’re least likely to find an electron

Question 8

How do unstable partially filled orbitals try to become stable?

Answer 8

-try to take up or lose electrons
-fill the orbitals = more stable

Question 9

What is an ionic bond?

Answer 9

-electron transferred from one atom to another
-orbitals are far apart in energy

Question 10

What is a covalent bond?

Answer 10

-2 electrons shared in 2 overlapping orbitals from 2 atoms
-orbitals have similar energy

Question 11

What nature do electrons have?

Answer 11

Wave and particle

Question 12

When electrons are shared, what happens with their waves?

Answer 12

They interact with each other, either constructively or unconstructively

Question 13

What happens when the 2 electron waves that interact with each other are identical?

Answer 13

-peaks + troughs match up
-resultant wave has peaks + troughs twice the size of the individual wave
-interfere constructively

Question 14

What happens when the peak of one electron wave matches with the trough of the electron wave that its interacting with?

Answer 14

-cancel each other out
-amplitude of resulting wave becomes 0
-destructive interference

Question 15

When 2 hydrogen atoms combine in phase, what happens?

Answer 15

• resulting hydrogen has lower energy than individual hydrogen atoms
  -electrons found in bonding molecular orbital

Question 16

When 2 hydrogen atoms combine out of phase, what happens?

Answer 16

-resulting molecule has higher energy than starting atoms
-electrons found in antibonding molecular orbital

Question 17

Are electrons more likely to be found in the antibonding or bonding molecular orbital?

Answer 17

Bonding molecular orbital

Question 18

What is the ground state?

Answer 18

The lowest energy level that an electron normally occupies

Question 19

How many unpaired electrons does carbon have in ground state?

Answer 19

2

Question 20

How many covalent bonds does carbon form to become stable?

Answer 20

4

Question 21

What is atomic orbital hybridisation?

Answer 21

Combining of atomic orbitals within an atom to form new orbitals

Question 22

How are hybrid orbitals formed?

Answer 22

Orbitals merge as they have similar energy in excited state

Question 23

In carbon, how are hybrid orbitals formed to allow it to make 4 covalent bonds?

Answer 23

-2s orbital merges with 2p orbitals to form 4 sp3 orbitals
-one electron in each hybrid orbital so can form 4 covalent bonds

Question 24

What happens when the s orbital and p orbital combine?

Answer 24

S orbital adds to one of the antinodes of the p orbital and subtracts from the other antinode

Question 25

What is the shape of methane and the angle between orbitals?

Answer 25

Tetrahedral - negative hybrid orbitals repel, so are far away from each other
109.5 degrees

Question 26

In methane, what does each orbital share an electron with?

Answer 26

A hydrogen

Question 27

What is a sigma bond?

Answer 27

-formed by the overlap of electron clouds in a straight line
-strongest covalent bond

Question 28

What orbitals are formed in ammonia and what is the angle between hydrogens?

Answer 28

-forms 4 hybrid orbitals: 2 electrons in 1 orbital + 1 electron in each of the remaining 3 orbitals
-one orbital with a lone pair of electrons
-107.3 degrees

Question 29

What orbitals are formed in ammonia and what is the angle between hydrogens?

Answer 29

-forms 4 hybrid orbitals: 2 electrons in 2 orbitals + 1 electron in each of the remaining 2 orbitals
-2 orbitals with lone pairs of electrons
-104.5 degrees