Module 3.1 The perodic table Flashcards
in the early 1800s what where the only two ways to categorise elements
- by their physical and chemical properties
- by their relative atomic mass
explain Dobereiner’s triads
he group elements with similar characteristics in threes and called them triads.
explain the law of octaves
Newlands order elements by mass and found similar elements appeared at regular intervals every 8th element was similar.
Mendeleev produced the first accepted version. what did his table contain
arranged elements by atomic masses.
left gaps where the next element didn’t seemed to fit.
he predicted the properties of undiscovered elements.
what do all elements in a period have in common
they all have the same number of electron shells (although not sub-shells)
period 1 has 1 electron shell and so on.
repeating trends in chemical and physical properties across the period due to this.
the trends that elements share in periods are known as
periodicity
what do all elements in the same group have in common
they all have the same number of electrons in their outer shell.
this causes them to also have similar CHEMICAL properties.
what does the group number tell you?
the number of electrons in the outer shell
s block elements contain which groups
groups 1 and 2
what is the outer shell electron configuration of elements in the s block
S(1) or S(2)
e.g Mg is 1s(2) 2s(2) 2p(6) 3s(2)
Li is 1s(2) 2s(2)
what part of the perodic table is the d block
the transition metals
what is the electron configoration of d block elements
outer shell is always a d sub shell
e.g cobalt: 1s(2) 2s(2) 2p(6) 3s(2) 3p(6) 3d(7) 4s(2)
(even though 4s fills first and so the last sub shell is 3d it is not written this way)
the p block contain which groups of elements
groups 3-7 and 0
what is the outer shell electron configurations of elements in the p block
from s(1)p(1) to s(2)p(6) e.g Cl: 1s(2) 2s(2) 2p(6) 3s(2) 3p(6)
period 1 can have what outer sub shell configeration
up to 1s(2)
period 2 can have what outer sub shell configeration
up to 2s(2) 2p(6)
period 3 can have what outer sub shell configeration
up to 3s(2) 3p(6)
ionisation is
the removal of one or more electrons
the first ionisation energy is
the energy needed to remove 1 mole of electrons from 1 mole of gaseous atoms.
you put energy in to ionise an atom so it is an
endothermic process
give the equation of the first ionisation of oxygen
O(g) –> O+(g) + e-
the lower the ionisation energy
the easier it is to form an ion
factors affecting ionisation energy are (3)
- NUCLEAR CHARGE
- ATOMIC RADIUS
- SHIELDING
nuclear charge affects ionisation energy how?
the more protons there are in nucleus the more ve+ charged the nucleus is and the STRONGER THE FORCE OF ATTRACTION for the electrons