chemistry of life L1

valence electrons

electrons in the outermost shell of an atom that are involved in chemical bonding and reactions. Chemical behavure of an atom is determined by the valance electrons

orbital

three demential space where the probability of finding an election is high

element

a pure substance consisting of one type of atom that cannot be broken down into simpler substances by chemical reactions

compound 

substance consisting of 2 or more elements in a fixed ratio 

matter

anything that takes up space and has mass.

ion

charged atom

covalent bond

the sharing of a pair of valance election by 2 atoms, the electrons count as part of each atoms valence shell.

molecule 

consitis of 2 or more atoms held together by covalent bonds 

electonegetivity

the relative attraction that an atom has for a shared pair of electrons in a covalent bond.

non polar covalent bond

a type of covalent bond where electrons are shared equally between two atoms, resulting in no partial charges. eg Dioygen (O2)

polar covalent bond

a type of covalent bond where electrons are shared unequally between two atoms, leading to a partial positive charge on one atom and a partial negative charge on the other. eg water (H2O) hydrogen

hydrogen bond

from when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom.

van der Waals interactions

attractions between molecules or parts of molecules as a result of charges caused by the uneven distribution of electrons in a molecule. they can be strong or weak.

polymer 

a long molecule.

molecular shape

determine how biological molecules recognise and interact with each other.

chemical equilibrium

is reached when the forward and reverse reactions occur at the same rate.

energy

the capacity to cause change, can’t be made or destroyed but change from one form to another.