Biochemistry definitions Flashcards
Chemistry
- the study of matter
- it’s chemical + physical properties
- chemical + physical changes it undergoes
Matter
anything that has mass + occupies space
Pure substance
only one component
Mixture
combination of two or more pure substances, each substance retains its own identity, not undergoing a chemical reaction
Element
- pure substance
- cannot be changed into simpler form of matter by any chemical reaction
Compound
pure substance from a combination of two or more elements in a definite, reproducable way
fixed ratio
Atom
smallest unit of an element that retains its chemical properties
Nucleus
- small, dense, positively charged region in centre of atom
- contais protons + neutrons
- electrons surround outside
Atomic number
number of protons in atom
Atomic mass
sum of protons + neutrons
Isotopes
- atoms of same element having different masses
- same number protons
- different number neutrons
- different chemical properties
Atomic orbitals
- regions in space with a high probability of finding an electron
- electrons do not move in orbits
Chemical bonding
- 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
Covalent bond
attractive force due to sharing of electrons between atoms
Ionic bond
attractive force due to the transfer of one or more electrons from one atom to another
Linear molecule
- 180 bond angle
- all electrons around central atom
- far as possible
- minimise electron repulsion
Trigonal planar structure
- 120 bond angle
- 3 bonded atoms around central atom
- minimal repulsion in triangular arrangement
Tetrahedral structure
- 109.5 bond angle
- 4 bonded atoms around central atom
- minimal electron repulsion in tetrahedron arrangement
Trygonal pyramidal
- 107 bond angle
- 3 bonded atoms
- 1 lone pair
- lone pair in separate corner so it doesnt distort arrangement of electron pairs
Non-linear
- 104.5 bond angle
- 2 bonded atoms
- 2 lone pairs
Single bond
- 154pm
- one pair of electrons shared between two atoms
- limited pull on nuclei
- longest length
- least stable
Double bond
- 134pm
- two pairs of electrons are shared between two atoms
- greater pull on nuclei
- bond shortened
Triple bond
- 121pm
- 180 bond angle
- three pairs of electrons are shared between two atoms
- shortest length
- most stable
Electronegativity
- 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
Polyatomic ions
- two or more atoms bonded together with overall positive or negative charge
- within ion there’s covalent bonding
Dispersion forces
- force of attraction between areas of two opposite charge
Electrolytes
ions present in solution allowing the solution to conduct electricity
Chemical reaction
a chemical substance is converted into one or more different substances by rearranging, removing, replacing or adding atoms
Catalyst
- 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
Bronsted-Lowry acid
proton donors
Bronsted-Lowry base
proton acceptors
Buffer
- resist pH changes when small amounts of acids or bases are added
- mixture of weak acids and conjugate base
Organic bond angles
triangular - 60
square - 90
pentagon - 108
hexagon - 120
Unsaturated hydrocarbon
- 120 bond angle
- planar around double bond
- no rotation
- fixed configuration
Heterocyclic aromatic compounds
- rings with at least one atom other than carbon as part of ring
- hetero atom usually O or N
- delocalised electrons
Aliphatic compounds
organic compounds that do not contain benzene ring
Thiols
- contain sulfhydryl group
- sulfur replaces oxygen
- S-H bond is less polar than O-H
Stereisomers
- connected in same order but differ in spatial arrangement
- cis/trans
- entantiomers
Entantiomers
- stereoisomers that are non superimposable mirror images
Chiral carbon atoms
carbon atoms that has four different groups bonded to it