Fundamental Chemistry

neutrons- neutral protons- positive electrons- negative

top number= atomic number- protons bottom number= atomic mass- protons + neutrons

element with the same number of protons and a different number of neutrons changes atomic mass same chemical characteristics

isotopes that are radioactive 14C can be used to determine age of artefacts measures decay of 14C using half life

differences in levels of metabolised testosterone can be measured (listen to recording)

electrons are found in orbitals held in place by electrostatic attractions electron shells fill sequentially

confused - listen to recording

atoms are stable when their outer shell is full of electrons atoms can gain (-ve) or lose (+ve) electrons to gain full outer shell atoms can join with other atoms to form molecules known as bonding

can be formed by sharing or transferring electrons ionic- electron transfer bond forms between metal and non metal eg NaCl covalent - electron sharing bond forms between non metals eg H2O metallic- share a sea of delocalised electrons between metals

high melting and boiling point- strong intermolecular forces (hard to break bonds) soluble in water- highly polar conduct electricity when in molten or aqueous solutions brittle- form lattice structure

valency refers to the number of covalent bonds an atom can produce low melting point and boiling point - weak intermolecular forces (volatile) low solubility in water- low polarity do not conduct electricity can form double/ triple covalent bonds

lattice made up of metal ions fixed in position surrounded by sea of delocalised electrons when voltage is applied, electrons move from high to low potential, forming current conduct electricity due to free moving electrons malleable (into sheets) and ductile (pulled into wires)

shape of molecule influences chemical behaviour shape of covalent molecule depends on number of electron pairs in outer shell electron pairs exist in a charge cloud clouds repel eachother

different atoms have different levels of electronegativity more electronegative will attract shared electron pairs towards them creates polar bond where electrongetaive atoms becomes -ve charge atoms of similar electronegativity do not form polar bonds

measure of the ability of an atom that is bonded to another atom to attract electrons to itself

polarity can be shown by labelling the end of being partially +ve or partially -ve charged non polar covalent= E<0.5 (eg ClCl) polar covalent= >0.5 E < 2 (eg HCl) ionic E>2 (eg NaCl)

polar molecules are more soluble in water steroid hormones are non polar and are not easily dissolved in blood/ urine polarity determines its ability to transport in/ out of cells

between molecules (covalent is intramolecular, within molecule) weaker than bonds between atoms stronger IMF, more energy required to break molecules apart gases- weak IMF liquid/solid - strong IMF

atoms and molecules exhibit LDF between themselves electrons orbiting nuclear create a cloud of neg charge large molecules have large electron clouds + strong LD interactions stronger LDF= higher boiling point

permanent dipoles eg HCl are in permanent state of polarisation + attract each other eg HCl will attract HCl eg hydrogen bonds (H covalently bonded to flourine, nitrogen or oxygen) are strong dipole dipole attraction

ionic compunds transfer electrons so atoms are permanently charged attracts atoms togther and forms large lattices structures bonds are very strong= high boiling point in solution the atoms dissociate (separate) + remain in their individual charged atom state

oxygen bonded to hydrogen and organic molecule eg carbon R group= carbon chains polar bond between O and H and O and R also called alcohols -OH

amine functional groups contain a nitrogen atom with a lone pair of electrons class of amine depends what else it is bonded to amino acid contain primary amine group- NH2 and R group secondary amine= NH and 2 R group tertiary amine= N and 3 R group