Biochemistry definitions

Question 1

Chemistry

Answer 1

• the study of matter
• it’s chemical + physical properties
• chemical + physical changes it undergoes

Question 2

Matter

Answer 2

anything that has mass + occupies space

Question 3

Pure substance

Answer 3

only one component

Question 4

Mixture

Answer 4

combination of two or more pure substances, each substance retains its own identity, not undergoing a chemical reaction

Question 5

Element

Answer 5

• pure substance
• cannot be changed into simpler form of matter by any chemical reaction

Question 6

Compound

Answer 6

pure substance from a combination of two or more elements in a definite, reproducable way
fixed ratio

Question 7

Atom

Answer 7

smallest unit of an element that retains its chemical properties

Question 8

Nucleus

Answer 8

• small, dense, positively charged region in centre of atom
• contais protons + neutrons
• electrons surround outside

Question 9

Atomic number

Answer 9

number of protons in atom

Question 10

Atomic mass

Answer 10

sum of protons + neutrons

Question 11

Isotopes

Answer 11

• atoms of same element having different masses
• same number protons
• different number neutrons
• different chemical properties

Question 12

Atomic orbitals

Answer 12

• regions in space with a high probability of finding an electron
• electrons do not move in orbits

Question 13

Chemical bonding

Answer 13

• force of attraction between any two atoms in a compound
• attractive force overcomes the repulsion of positively charged nuclei of the two atoms participating in bond
• interactions involving valence electrons are responsible for chemical bond

Question 14

Covalent bond

Answer 14

attractive force due to sharing of electrons between atoms

Question 15

Ionic bond

Answer 15

attractive force due to the transfer of one or more electrons from one atom to another

Question 16

Linear molecule

Answer 16

• 180 bond angle
• all electrons around central atom
• far as possible
• minimise electron repulsion

Question 17

Trigonal planar structure

Answer 17

• 120 bond angle
• 3 bonded atoms around central atom
• minimal repulsion in triangular arrangement

Question 18

Tetrahedral structure

Answer 18

• 109.5 bond angle
• 4 bonded atoms around central atom
• minimal electron repulsion in tetrahedron arrangement

Question 19

Trygonal pyramidal

Answer 19

• 107 bond angle
• 3 bonded atoms
• 1 lone pair
• lone pair in separate corner so it doesnt distort arrangement of electron pairs

Question 20

Non-linear

Answer 20

• 104.5 bond angle
• 2 bonded atoms
• 2 lone pairs

Question 21

Single bond

Answer 21

• 154pm
• one pair of electrons shared between two atoms
• limited pull on nuclei
• longest length
• least stable

Question 22

Double bond

Answer 22

• 134pm
• two pairs of electrons are shared between two atoms
• greater pull on nuclei
• bond shortened

Question 23

Triple bond

Answer 23

• 121pm
• 180 bond angle
• three pairs of electrons are shared between two atoms
• shortest length
• most stable

Question 24

Electronegativity

Answer 24

• a measure of the ability of an atom to attract elements in a chemical bond
• high electronegativity = easier to attract electrons
• greater difference in electronegativity = more polar bond

Question 25

Polyatomic ions

Answer 25

- two or more atoms bonded together with overall positive or negative charge - within ion there's covalent bonding

Question 26

Dispersion forces

Answer 26

- force of attraction between areas of two opposite charge

Question 27

Electrolytes

Answer 27

ions present in solution allowing the solution to conduct electricity

Question 28

Chemical reaction

Answer 28

a chemical substance is converted into one or more different substances by rearranging, removing, replacing or adding atoms

Question 29

Catalyst

Answer 29

- substance that increases reaction rate - undergoes no net change - does not alter final product of reaction - interacts with the reactants to create an alternative pathway for product production

Question 30

Bronsted-Lowry acid

Answer 30

proton donors

Question 31

Bronsted-Lowry base

Answer 31

proton acceptors

Question 32

Buffer

Answer 32

- resist pH changes when small amounts of acids or bases are added - mixture of weak acids and conjugate base

Question 33

Organic bond angles

Answer 33

triangular - 60 square - 90 pentagon - 108 hexagon - 120

Question 34

Unsaturated hydrocarbon

Answer 34

- 120 bond angle - planar around double bond - no rotation - fixed configuration

Question 35

Heterocyclic aromatic compounds

Answer 35

- rings with at least one atom other than carbon as part of ring - hetero atom usually O or N - delocalised electrons

Question 36

Aliphatic compounds

Answer 36

organic compounds that do not contain benzene ring

Question 37

Thiols

Answer 37

- contain sulfhydryl group - sulfur replaces oxygen - S-H bond is less polar than O-H

Question 38

Stereisomers

Answer 38

- connected in same order but differ in spatial arrangement - cis/trans - entantiomers

Question 39

Entantiomers

Answer 39

- stereoisomers that are non superimposable mirror images

Question 40

Chiral carbon atoms

Answer 40

carbon atoms that has four different groups bonded to it