AS chemistry revision

mass of an electron

1/2000th of a proton

metals generally for ions by _______ electrons with a(n) ______ in oxidation number to form ______ ions

1: losing 2:increase 3:positive

elements in a group have similar ______ _______ ________ _________, resulting in similar _________

1: outer electron configurations 2: properties

non-metals generally for ions by _____ electrons with a(n) _____ in oxidation number to form ______ ions

1:gaining 2:decrease 3:negative

Avogadro number

6.23 x 10^23 (number of particles per mole)

use of Ca(OH)2 and Mg(OH)2

Ca(OH)2: neutralizes soil acidity in agricultural Mg(OH)2: neutralizes stomach acid

an acid releases ____ _________ in an aqueous solution

H+ ions

In what molecules can hydrogen bonds form?

N, O, F

common ions

NO3, CO3(-2), SO4(-2), NH4(+1)

hydrated

a crystalline compound containing water molecules

what may arise when covalently bonded atoms have different electronegativities and what will it result in?

a permanent dipole and it results in a polar molecule

orbital

a region that can hold up to 2 electrons with opposite spins

Periodicy

a repeating pattern across differant periods

covalent bond

a shared pair of electrons

how do van der waals forces arise?

an uneven distribution of electrons at any point in time causing an instantaneous dipole in a neighboring atom attracting the atoms to one another

isotopes

atoms of the same element with a different mass number and number of neutrons

what is used as the standard measurement of relative masses?

carbon-12

ionisation energy has a general _______ down a group

decrease (increase radius, increase shell => increase shielding which overcomes the increase in nuclear charge)

reactivity ________ down group 7

decreases (due to increase in atomic radius and more shielding, less attraction between outer electrons and nucleus, therefore it attracts electrons less and the electronegativity is less)

p orbital shape

dumbbell shape

redution

gain of electrons (decrease in oxidation number)

common acids

hydrochloric acid: sulfuric acid: nitric acid:

ionisation energy has a general ___________ across a period

increase (greater nuclear charge, little/no diff. in shielding)

reactivity ___________ down group 2

increases (due to increase in atomic radius and more sheilding, less attraction between nucleus and outer electrons, therefore loses electrons more easily)

oxidation

loss of elections(increases in oxidation number)

molar mass

mass per mole of a substance (units= g/mol)

common bases

metal oxides, metal hydroxides, and ammonia

the unit for "amount of a substance"

mole

need to know formulas

n=g/Mr n=CV n=V/24dm^3 n x Avogadro number= number of mulectules

ionization energies are affected by:

nuclear charge, electron shielding and the distance from the outer most electron to the nucleus

salt

produced when the H+ ion of an acid is replaced by a metal ion or NH4+

relative charge and relative mass of a proton, neutron, and electron

proton: charge=+1 mass=1 neutron: charge=0 mass=1 electron: charge=-1 mass=1/2000th

disproportionation

reaction in which an element is both reduced and oxidised

what is the shape of a simple molecule determined by?

repulsion between electron pairs surrounding a central atom (lone pairs repel more than bonded pairs)

acid+carbonate=

salt+CO2+ H2O

acid+metal=

salt+H2

aid+base=

salt+H2O

common alkalia

sodium hydroxide: potassium hydroxide: aqueous ammonia:

alkali

soluble base that releases OH- ions in an aqueous solution

s orbital shape

spherical

electronegativity

the ability of an atom to attract the bonding electrons in a covalent bond

molecular formula

the actual number of atoms of each element in a molecule

metallic bonding

the attraction of positive ions to delocalised elecrons

ionic bonding

the electrostatic attraction between oppositely charged ions

first ionazation energy

the energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions

ionization energy

the energy required to remove one electron from each atom in one mole of molecules in the gaseous state

atomic number

the number of protons in the nucleus of an atom

empirical formula

the simplest whole number ratio of of each atom of an element present in a compound

mass number

the sum of the number of neutrons and protons in an atomic nucleus

relative atomic mass

the weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon-12

relative isotopic mass

the weighted mean mass of an atom of an isotope compared with one-twelfth of the mass of an atom of carbon-12

water of crystallization

water molecules that form an essential part of the crystalline structure of a compound

when do you state the oxidation state of an element using roman numerals?

when it may be ambiguous otherwise

dative covalent bond

when the shared pair of electrons comes from only one atom

anhydrous

without water