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Biochemistry and Cell Biology Semester 1 > Fundamental Chemistry > Flashcards

Fundamental Chemistry Flashcards

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1
Q

structure of an atom

A

nucleus - protons +ve mass 1
neutrons 0 mass 1
electrons orbit -ve mass 0
(results in nucleus +ve and heavy)

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2
Q

describe element composition

A

top no. = proton/atomic number
bottom no. = proton+neutron/atomic mass
protons and electrons are =

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3
Q

as you move across the periodic table …

A

elements gain more protons

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4
Q

as you move down the periodic table …

A

there are more concentric circles of electrons

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5
Q

whats an isotope and what changes

A

the same element with different no. of neutrons (changes atomic mass but not chemical properties as charge remains the same

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6
Q

why are atomic masses not usually a whole number

A

due to many isotopes of the same element

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7
Q

what is carbon dating

A

using the isotope 14C which is radioactive to measure how old something is

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8
Q

whats the half life of 14C and why is that important

A

5730 yrs and is fixed so at death, organic ,matter has 100% of its 14C, 5730 yrs later it will only have 50% of 14C

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9
Q

what are anabolic steroids and how are they tracked

A

elemental isotopes - when testosterone or DHEA is metabolised into androsterone naturally there is specific ratios of 12C and 13C. when synthetically added there is a different ratio however difficult to track due to varying diets

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10
Q

what stops electrons flying away

A

attraction between +ve nucleus and -ve electrons

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11
Q

where are electrons found

A

orbitals

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12
Q

whats the octet rule

A

when electron shells fill sequentially

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13
Q

why are noble gases inert (don’t react)

A

they have a full outer shell of electrons (stable octet)

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14
Q

how to calculate an elements atomic mass with isotopes

A

isotope no. x %abundance + any other isotope / 100

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15
Q

ionic bonding

A

metal x non metal
transferring electrons

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16
Q

covalent bonding

A

non mental x non metal
share electrons

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17
Q

metallic bonding

A

share a sea of delocalised electrons
metal x metal

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18
Q

ionic bonding example NaCl

A

Na atomic no. = 11 (2,8,1)
Cl atomic no. = 17 (2,8,7)
Na needs to donate e- (becomes +ve)
Cl needs to gain e- (becomes -ve)

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19
Q

properties of ionic bonding

A

high melting and boiling due to permanent charges forming strong intermolecular forces
soluble as polar
conduct electricity in solution as free movement of charge
brittle as sheets of lattice can slide

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20
Q

covalent bonding example H2O

A

H atomic no. - 1
O atomic no. = 8 (2,6)

2xH atoms share each of their electrons (one bond) to fill one O outer shell to 8 by forming 2 bonds

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21
Q

covalent bonding properties

A

low melting and boiling as no charge so weaker intermolecular forces
low solubility
don’t conduct electricity and no free movement of electrons

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22
Q

double covalent bond example CO2

A

C has 4 electrons in outer shell (requires 4 to be stable)
O has 6 electrons so requires 2
C shares 2 electrons with each O forming 2 double bonds

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23
Q

triple covalent bonds example hydrogen cyanide

A

C shares 4
H shares 1
N shares 3

(C-H is one bond sharing 1 electron)
C-N is three bonds sharing remaining 3 electrons)

24
Q

metallic bonding properties

A

sea of delocalised electrons means conduction of electricity and malleable

25
Q

importance of molecular shapes

A

influences chemical behaviour
recognition and response to other molecules

26
Q

sub levels of energy in electron shells

A

s = up to 2 e (1pair)
p = up to 6 e (3pairs)
d = up to 10 e (5pairs)
f = up to 14 e (7pairs)

(e exist in pairs so each orbital is a pair)

27
Q

how do the shapes of molecules form

A

depends on no. of electron pairs in outer shell
they exist in a charge cloud which repel each other so want to be as far apart as possible
not uniform as if not shared they repel more

28
Q

shapes of molecules example BeF2 linear

A

2 pairs around central atom
F = 1 pair Be = 2 spare
2xF contribute to sharing e-
all e- in outer shell are involved
most energetically favourable way to separate is 180 degrees (straight Line F-Be-F)

29
Q

what causes different molecular shapes to form

A

lone pairs of electrons which have more repulsion

30
Q

why does molecular shape matter

A

results in polarity eg
CO2 all e- involved = linear (O-C-O) with charge cancelled out so non polar
H2O has 2 spare pairs forming 2 dipoles with O -ve and H +ve and therefore polar

31
Q

whats electronegativity

A

ability of an atom to attract electron density towards itself (pulling the -ve causing temporary charge)

32
Q

whats electronegativity measured in

A

ability of an atom that is bonded to another to attract electrons to itself (each element given a value between 3.98-0.79)

33
Q

what happens to electronegativity moving left along periodic table

A

increases due to outer shell staying same distance from nucleus but nucleus gains more neutrons and protons (more +ve) so the pull from nucleus is stronger

34
Q

what happens to the electronegativity moving down the periodic table

A

decreases as outer shell gets further away so the pull is lower and easier to steal e-

35
Q

whats the electronegativity for non polar covalent bonds

A

delta E <0.5

36
Q

whats the electronegativity for polar covalent bonds

A

> 0.5deltaE<2

37
Q

whats the electronegativity for ionic bonds

A

deltaE>2

38
Q

how to calculate electronegativity of a molecule

A

net difference in value = deltaE

39
Q

what determines level of polarity

A

difference in electronegativity between the 2 atoms in the bond
egblue = lower electron density red = higher
the larger the delta E the more electrons are drawn from one end to the other

40
Q

why is polarity important

A

polar molecules are soluble in water
steroids are non polar so don’t dissolve easily in blood
transportation in and out cells

41
Q

intramolecular vs intermolecular forces

A

intra within eg covalent
inter between molecules (weaker)

42
Q

how are London dispersion forces formed

A

constant motion of electrons in the cloud causes temporary charges to form so +ve and -ve attract

43
Q

dipole dipole attractions

A

permanent state of polarisation causes. molecules to attract to teach other eg HCl as Cl is -ve and H is positive due to withdrawal of electron density towards Cl

44
Q

water and hydrogen bonds

A

O is electronegative and draws electrons from H forming delta -ve O and +H

45
Q

intermolecular forces with ionic bonding

A

ionic means transfer of electron = permanent charge attracting atoms together = lattice = high boiling point

46
Q

importance on ionic bonds in biology

A

determine shells of proteins
ionic solution maintain cell potentials
muscle contraction as a result on ion movement

47
Q

whats a functional group

A

an arrangement of atoms that’s responsible for chemical characteristics found along carbon backbone of organic molecules

48
Q

hydroxyl group

A

one form
O2 boned to H and organic molecule (carbon)
polar bond between O and H and O and R

49
Q

amine group

A

contains N and lone pair of electrons
class depends on what else is bonded eg
primary 1xR secondary 2xR tertiary 3xR
(AA primary)

50
Q

carbonyl group

A

carbon double bonded to O2 and 2xside chains
C +ve and O2 electronegative = polar

51
Q

acid vs base/alkaline

A

acid = more H+ ions

52
Q

importance of ph in biology

A

requires specific ph to function
eg exercise increases H+

53
Q

Avogardos constant

A

the mole = 6.02x10^23

54
Q

whats molecular concentration

A

number of moles of a substance in a defined volume (1 mole of a molecule is always its molecular weight)

55
Q

calculation of molarity

A

Mass = Molecular weight x Moles
Molecular weight = Mass/Moles
Moles = Mass/Molecular weight

Biochemistry and Cell Biology Semester 1 (12 decks)

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