Periodicity Flashcards
What is the atomic number?
The number of protons
The periodic table is arranged in rows whish are based on
The increasing number of protons (atomic number)
Groups are organized based on..
valence
What is the number of valence electrons of groups 1 & 2
= Group number so
Group 1 = 1 valence
Group 2 = 2 valence
What are the valence electrons for Groups 13 - 18
= Group number - 10
Exception for helium has 2 valence electrons
Elements in the same group also have similar properties, these include …
Group 1 : alkali metals (except Hydrogen)
. Relatively soft, highly reactive with oxygen and water.
Group 2: Alkaline earth metals
Group 17: Halogens
. Coloured and highly reactive
Group 18: Noble Gases
. Low reactivity (quite stable electron arrangements)
Periods are
Horizontal rows 1-7 and resonate info about electron configuration (number shows highest occupied shell)
Blocks are
labeled in order sdpf and elements within correspond to highest occupied energy subshell.
Melting points are seen…
increasing acroos groups 1-14 and drop for groups 15-18
Trends within blocks in table include
- S block: solids except hydrogen (gas)
- D block: solid except mercery (liquid)
- P block: some solid and some gas
- Noble gasses: Group 18 + nitrogen, oxygen, fluorine, chlorine
- bromine = liquid
Electron configuration trends include:
- Increase moving down a group because the number of electron shells increases, meaning weaker attraction to nucleus
Core charge is
the measure of attractive force felt by the valence electrons towards the nucleus
Core charge trends across the periodic table include:
- Going down a group core charge stays because the number of inner shell electrons and protons increase proportionally.
- Going left - right across a period core charge increases because the number of protons across a period increases while the electron shells relatively stay the same, making the attraction towards the nucleus significantly stronger.
How do you calculate cor charge?
number of protons - number of inner shell electrons.
Electronegativity is
the ability of an atom to attract electrons towards itself
Trends regarding electronegativity include
- increases going across periods because as the core charge increases, and the atomic radius decreases, leads to a stronger attraction for bonding electrons.
- decreases going down because the atomic radius increases meaning less attraction towards the nucleus and electrons are easier to remove for bonding
Atomic radius is:
the measurement used for size of atoms
Atomic radius trends include…
- decreases across a period, because the attraction of electrons gets stronger
- increases going down a group, because core charge remains but electron shells increase making attraction weaken.
Ionization is, trend?
the process of removing an electron form an atom and forming an ion. Increases across a period.
Reactivity is …
how easily an element can loose or gain electrons, decreases across, increases down.
Non - metal reactivity trend includes..
decreases down, increases across.
