periodic table + periodic trends Flashcards
atom
neutral particle
basic building block of metal
protons
p+
positively charged sub atomic particles
neutrons
n o
neutral sub atomic particles
nucleons
p+ and n o
sub atomic particles
atomic number
z
number of protons
mass number
A
no. of protons+ neutrons> nucleons
isotopes
atoms of same element (same p+) w diff. mass numbers
have diff properties to og element
ions and types
charged atoms
cations: + charged atoms, tend to lose e-
anions: - charged atoms,tend to gain electrons
group 1
alkali metals most reactive of all metals reactivity increases down group found in compounds -have single valance e- react with cold water producing hydrogen and hydroxide soft + light grey
group 2
alkaline earth metals reactive 2 valance e- -somewhat less reactive than group 1 all except Br react w cold water forming hydrogen and hydroxide light grey, relatively soft good conductors
group 17
halogens very reactive - found in compounfs form salts when react w metals have 7 valance e- — gain 1 e- reactivity decreases down group -atomic radius increases
low melting points
group 18
stable noble gases
unreactive- full valance energy levels
gases at room temo
group similarities
same valance e- (of group no.)
elements have similar chem. properties
metals
left side of periodic table up to and including post transition metals
few valance e-
lose e- — cations
non metals
right side of periodic table + including metalloids
large no. of valance e-
accept/gain e- to complete energy level—anions
atomic radius
distance of an atom from its nucleus to its outermost section
decreases as goes up descending periods
increases as goes left groups
explainibg atomic radius across perioid
from left to right across a period, the net attraction force of the nucleus to each electron increases, as number of protons in the nucleus increases.
a greater force of attraction means a smaller distance between the nucleus+valance e- and a smaller atomic radius
explaining atomic radius from top to bottom down a group
from top to bottom down a group the number of energy levels increases
more energy levels result in larger atomic racius
valance electrons
e- in the outermost energy level
group number
valance energy level
outermost energy level
energy levels=period number
core electrons
e- in the full inner energy levels
diatomics
N -F, F- I
unpaired e-
e- of valance e- does not have partner e-
lone pairs
paired e- of valance e-
valency number
charge atom would have if it were an ion
to become stable
end of metals
Al
Ge
Sb
Po
ionisation energy
amount of energy required to remove 1 electron from single atom in gaseous phase
inversely proportional to atomic radius
if atomic radius larger-removing e- easier, e- further from positive nucleus
smaller the atom,closer e- is to nucleus, more tightly bound to nucleus, will require more energy
first ionisation energy
energy required to remove first e-
huge ionisation energy
removing core e-
why is it harder to remove e- as atom becomes smaller
closeer to positive nucleus
requires a lot of energy
ionisation energy from left to right across a period
from left to right across a period the net attraction force of the nucleus to each electron increases as the number of protons in the nucleus increases.
A larger force of attraction means a smaller distance between the nucleus and valance e- and a smaller atomic radius.
A large force of attraction means that more energy is required to overcome forces to remove e-.
from top to bottom down a group
from top to bottom down a group the number of energy levels increases (increasing atomic radius)
valance electrons are increasingly shielded from the positive nucleus by core electrons
this results in a smaller/weaker force of attraction on each e-
a weaker force of attraction means that more energy is required to overcome forces to remove e-
electron shielding
barrier of negative energy level shields charge of positive charge
inner energy levels shield the positive charge of nucleus on valance e-
anomalies
things that don’t follow the trend
anomalies in ionisation energy
boron +beryllium
In boron the valance e- to be removed is in a P orbital
this electron is further from the nucleus + experiences a weaker force of attraction to the positive nucleus
less energy required to remove this e-
(lower ionisation energy than expected)
anomalies in ionisation energy
N to O
In oxygen, the valance e- to be removed is in a p orbital that already has an e-.
the valance e- is repelled slightly by this electron meaning less energy is required to remove it
electron affinity
amount of energy released when e- is added to a single atom in the gaseous phase (nm gain).
atoms w a greater affinity for e- release more energy when they gain e-
trend same as ionisation energy
electron affinity trends
from left to right across a period the number of protons in the nucleus increases
the affinty for an e- increases
more energy released when e- added
from top to bottom down a group the number of energy levels increases (increasing atomic radius)
more energy levels means more e- shielding of positive nucleus
affinity for e- decreases, less energy is released when e- added
electronegativity
indication of attractive force which an atom exerts on shared e- pair
measured on scale of 0-4
density of metals trend
from left to right across a period , atomic radius decreases while atomic mass increases
thus density of metal increases
top to bottom in a group: atomic radius increases, mass of atoms increases resulting in increase in density
melting and boiling point trends
moving left to right across period for groups 1-14 melting+boiling increase mp+bp of groups 15-18 v low top to bottom in groups 1+2, decrease top to bottom groups 17+18, increase
