Periodic table Flashcards
How are elements arranged in the periodic table
Elements are arranged in the order of increasing atomic number
what are rows
periods: number of occupied electron shells
what are columns
groups: number of outermost shell/ valence electrons
properties of group 18/0
they are noble gases and all are colourless gases that are very stable and inert because they have already had either duplet structure or octet structure, giving extra stability to the atoms.
chemical properties of transition elements
- Form compounds with more than one charge
- Form a variety of complex ions
- Form coloured compounds
- Act as catalyst when in either the form of elements or compounds
what is region 1 and 2 considered
It is the s block and p block and they are regarded as representative or main group elements.
which group are metals and what is the exception
Group 1, group 2 and
group 3 except boron are metals
physical properties of group 1,2,3
shiny appearance, malleable, ductile and good electrical and thermal conductivity
When reacted, they tend to lose electron(s) to form cations.
what does region 3 consist of
It is the d block and consists of transition elements
what does region 4 consist of
It is the f block and consists of lanthanides and actinides, which interrupt periods 6 and 7 on the Periodic
table.
properties of group 4 to group 7 elements
● Most of the elements in groups 4 to 7 are non-metals which lack distinctive physical properties that characterize them.
● Most of them are poor conductors of heat and electricity.
● When they react, they tend to gain electron(s) to form anions.
properties of metalloids/semi-metals
● They have properties in between those of metals and non-metals.
● Typical metalloids have a metallic appearance, but they are brittle and only fair conductors of electricity.
● Chemically, they mostly behave as non-metals.
e.g. boron and silicon
physical properties of transition elements
- High electrical and thermal conductivity
- High melting point
- Malleable
- Ductile
properties of f-block elements
Lanthanides (Z = 58 to 71) are reactive, silver-coloured metals that tarnish when exposed to air.
Actinides (Z = 89 to 103) are similar to typical metals but they are radioactive.
properties of group 1 metals
they are alkali metals, The elements in this group are shiny and silvery metals. They are generally soft and can be easily cut with a knife. Since they are very reactive, they should be stored in paraffin oil (a non-aqueous solvent)
to prevent them from contact with air and moisture / water.
properties of group 2 metals
They are called alkaline earth metals, they show similar properties (shiny, silvery, soft, cut with knife, paraffin oil, prevent moisture and air) to those in group 1 but less reactive
Denser and harder than group 1 metals
why does the reactivity of group 1 and 2 metals increase down the group
Reactivity of group 1 and 2 metals increases down the group, because of
the increasing trend of atomic radius.
what is atomic radius
half of the distance between the nuclei of two neighbouring atoms
what does atomic radius refer to
It refers to the distance from the nucleus to the outermost shell/valence
electrons of the atom.
why does an increasing trend of atomic radius affect the reactivity
● Going down these two groups, the number of occupied electron shells of the atoms increases.
● The electrostatic force of attraction between the nucleus and the outermost shell electrons becomes weaker.
● Less energy required to remove this
outermost shell/valence electron
what is the energy required to remove the outermost shell electron called and what is it
This energy is referred as ionisation energy (I.E.), which is the minimum
amount of energy required to remove one mole of electrons from one
mole of gaseous atoms at ground state.
equation of ionisation energy
Equation: X (g) → X+ (g) + e-
properties of group 17/7
they are called halogens and the elements in this group are all poisonous and reactive non-metals. They have different colour and physical states under ambient conditions
colour of fluorine, chlorine, bromine and iodine
fluorine : pale green gas
chlorine : pale green gas
bromine : reddish brown liquid
iodine : black solid
reactivity of halogens when going down the group
● Reactivity of these elements decreases down the group
● because the atomic radius of these elements increases.
● The electrostatic attraction between the nucleus and the additional electrons becomes weaker.
In other words, the affinity for an electron decreases.
what is electron affinity (E.A)
It is the energy released when one mole of gaseous atoms gains one mole
of electrons.
equation of electron affinity
X (g) + e- → X- (g)
