2.perodic table and bonding
perodic table
table shows all known elements shows elements in order of atomic number laid out in elements with simmilar properties form columns
vertical columns
called groups
elements
have same number of electrons in outer electrons.atomic number equal to number of electrons each atom has
electron shells
electrons always occupy shells(energy levels) lows enerrgg levels filled first only certain n.o electrons allowed in each shell 1st shell 2 .2nd shell 8 3 rd shell 8
metals
left of zig zag classfied as metals conduct electricity conduct electricity allow charge to pass through easiliy metal kxides basic neutralize acids .metal oxides thet wull dissokve form solutions with pH more than 7
non metals
right of zigzag acidic neutralize bases dissolve water form solutions with pH less than 7
group 0 elements
inert,colourless gasses called noble gasses.inert dont react takes lot of energy + or remove electrons from noble gases
ions
simple ions form when atoms lose or gain electrons.ions charged particles can be singke atoms Na+ or groups of atoms e.g No-3
negative ions(anions)
form when atoms gain electrins have more electrons than protons
positive ions(cations)
form when atoms lose electrons more protons than electrons n.o electrons lost or charged group 1.2.3 metals lose electrons from positive ions 5,6,7 non metals gain electrons for negative ions
how many ions in each group
group 1-1+ ion group 2- 2+ ion group 3 3+ ion group 5 3- ions group 6- 2-ions group 7- 1-ion
ionic bonding
transfer of electrons produces ionic compound metal reacts with non metal (group 1+ group7) metal atom loses electrons to form a positive ion (cation) non metal gains these electrons form negative ion (anion) opositely charged ions strongly attracted to one another by electrostatic attraction called ionic bond
sodium chloride(NaCl)
sodium atom gives up outer elctron becoming an Na + ion. chlorine atom picks up electron becoming Cl- chloride ion
magnesium oxide(MgO)
magnesium atom gives up 2 outer electrons becoming Mg2+ ion .oxygen atom picks up the electrons becoming O2- oxide ion
aluminium chloride(AlCl3)
aluminium atom gives up 3 outer electrons becoming an Al3+ ion chlorine atoms pick up 3 electrons becoming 3Cl- ions
Sodium Oxide (Na2O)
2 sodium atoms each give up outer electrons becoming 2Na+ ions.oxygen atom picks up 2 electrons becoming 02 - ion
ionic compounds
made up of a positively charged part and negatively charged part.overall charge any ionic compound is 0.all negative charges in compounds must balance all positive charges
ionic compound structure
lattice structure. giant ionic structures.ions held together closely packed 3D lattice arrangement by attraction between oppositely charged ions
ionic compound properties
all have simmilar properties.electrostatic attraction between oppositely charged ions is very strong. lot of energy needed to overcome strong attraction .have high melting/boiling points. not electrical conductors when solid if melt or dissolve in water able to conduct electricity
covalent bonding
contain shared pairs of electrons sometimes atoms make covalent bonds by sharing pairs of electrons with other atoms. each covalent bond provides 1 extra shared electron for each atom.strong electrostatic attraction between negatively charged shared electrons (bonding pair) and negatively charged nuclei of atoms involved
hydrogen H2
1 electron outer shell can only fit 1 more electron in that shell hydrogen atoms can form 1 covalent bond
Chlorine Cl2
7 electrons in outer shells fit 1 more in shell can form 1 covalent bond
hudrogen chloride HCl
each atom can only fit 1 more electron in outer shell form 1 covalent bond
ammonia NH3
nitrogen 5 electrons outer shell fit 3 more electrons.ammonia forms 3 covalent bonds 1 each with 3 hydrogen atoms
nitrogen N2
can only fit 3 more electrons in outer shell 2 nitrogen atoms can share 3 pairs of electrons creates tripple covalent bond
oxygen O2
has 6 electrons in outer shell can fit 2 more electrons in shell. in oxygen gas 2 oxygen atoms share 2 pairs of electrons to form double covalent bonds
water H2O
water molecules 2 hydrogen atoms each share pair of electrons wirh an oxygen atom to form 2 covalent bonds
methane CH4
carbon has 4 electrons in outwr shell can put 4 more electrons in shell.methane forms 4 covalent bond -1 each with 4 hydrogen atoms
carbon dioxie CO2
has 2 oxygen atoms each share 2 pairs of electrons with a carbon atom forms 2 double covalent bonds
chloromethane CH2Cl
a Cl atom can only fit 1 more electron in outer shell carbon forms 4 covalent bonds -1 each sith hydrogen atoms and 1 with chlorine atoms
ethane C2H6
6 hydrogen atoms esch share outer electron with 1 or 2 carbon atoms.2 carbon atoms also share 1 outer electron with each form single covalent bonds
ethene C2H4
4 hydrogen atoms each share outer electron with 1 or 2 carbon atoms 2 carbon atoms also share 2 outer electrons with each other to form carbon-carbon double bond
simple molecular substances
forces of attraction weak .atoms within molecule held together by very strong covalent bonds.melting /boiling pounts low because molecules easiliy seperated.
intermolecular forces
stronger between molecules high relative mass(Mr) between smaller molecules.more energy needed to break forces. most molecular substances are gases or liquids at room temp
giant covalent structures+ fullerness
no charged ions. all atoms bonded to eachother by strong covalent bonds lots of these bonds which means it takes lot of energy to break . are solids high meltiing/boiling points dont conduct electricity insoluble in water eg diamand+ graphite made from carbon atoms
diamond
very hard.made of network of carbon atoms each form 4 covalent bonds.strong covalent bonds take lots energy to break high melting point .strong covalent bonds hold atoms in rigid lattice structure makes diamond hard doesnt conduct elefyricity no free electrons or ions
graphite
contains sheets of hexagons. each carbon forms 3 covalent bonds creating layers of carbon atoms.layers held together weakly by intermolecular forces free to slide over each other makes graphite soft+slippery high melting point-covalent bonds in layers need loads of energy to break .only 3 out of each carbond 4 outer electrons used in honds.each carbon atom has 1 electron delocalised (free) to move non metal conductors
C60 fullerene
simple molecular substance hollow spheres made of 60 carbon atoms made of large covalent molecules. held together by intermolecular forces+ can slide over eachother material is soft.1 delocalised electron.electrons cant move between molecules poor conductors of electricity
electrical condicitvty+ metals
electrical current is flow of electrons or ions electrons have negative charge. ions have positive or negatige charge. when electrons or ilns move cause material to conduct electricity . electric current is flow of electrons or ions
ionic compounds
molten+ dissolved ionic compounds conduct electricity made of lattice of positive+ negative ions solid ionic compounds dont conduct electricity because ions arent able to move around ionic compound dissolved ions seperate+ able to move in solution.compound will conduct electricity.ionic compound melts ions able to move conduct electricity
metals
held together by metalic bonding.giant structure of postive ions surronded by sea lf delocalised electrons.electrostatic attraftion between nuclei of positive ions + electrons called metalic bonding which gives metal properties.good conductors of electricity + heats delocalised electrone able to move through strucure metals can conduct electricity
metal properties
movement of electrons means energy can be transferred quickly through material conductorsbof head.malleable.layers of ions in metal slide over each other making metals malleable can be hammered and rolled in flat sheets