Unit 1 - Chemical Changes and Structure Flashcards
Covalent radius
Half the distance
between the nuclei of 2 of its bonded atoms.
What happens to the covalent radius as you go
across a period?
It decreases due to increased atomic number.
What happens to the covalent radius as you go down
a group?
It increases due to increased electron shielding.
Ionization energy
The energy required to remove one mole of electrons
from one mole of atoms in the gaseous state
The strength of metallic bonding _____ as you go along a period.
Increases, due to increased numbers of delocalized electrons.
The strength of
metallic bonding
________ as you
go down a group
Decreases.
Intramolecular forces
The strong attraction between atoms and molecules
Intermolecular forces
The weak attraction in-between different molecules
Three types of Van der Vaals intramolecular forces
- London dispersion forces
- PD-PD
- hydrogen bonding
What molecules create hydrogen bonding?
NH, OH or FH
Electronegativity
Electronegativity is a measure of the attraction an atom involved in a bond has for the electrons in a bond.
Elements at the top________ hand side of the periodic table e.g. F .0, N are the _______electronegative.
Right, most.
Elements at the bottom _______ hand side of the periodic table e.g. K, Rb, Cs are the ______ electronegative.
Left, least.
Electronegativity ________________ as we go along a period.
Increases.
Electronegativity ________________ as we go down a group.
Decreases.
The strength of London dispersion force _______ as the size of the atoms increase.
Increases.
Covalent molecular substances have ______________melting points and boiling points
Low.
Within covalent molecules there are strong _____________ bonds
Intramolecular.
Polymorphs are___
different crystalline forms of the same element
Fullerenes are a large family of ‘carbon cage’ molecules each made up of rings of _____ and _____ carbon atoms.
5&6
C60 is called..
Buckminsterfullerene
With no ‘free’_____________ fullerenes are normally poor conductors
Electrons
Nanotubes are…
fullerenes made from ‘tubes’ of 6-carbon rings rather like a rolled up sheet of graphite
polymorphs of carbon
diamond & graphite
In diamond, each Carbon is joined to ____ others in a ______
4 & tetrahedral network structure
In graphite, each Carbon is joined to ____ others in a ______
3 & layers with a hexagonal arrangement of atoms
The noble gases exist as …………………… atoms with ……………………………. between the atoms.
monatomic & LDFs
Covalent molecular compounds are…
made of discrete particles with a definite formula
Covalent network compounds are…
made of a giant lattice of atoms covalently bonded
Covalent bonding is…
the attraction of the shared electrons for the nuclei of both the bonded atoms
Water molecules are _____________ in shape.
angular
Hydrogen bonding is _______ than LDFs
stronger
Types of Van Der Waals’ forces
London dispersion forces, PD-PD interactions and hydrogen bonding
Elements which can hydrogen bond
FON
Because it is polar water is useful as a ______ for ionic compounds.
solvent
like dissolves like
like dissolves like
______ is an excellent oxidising agent.
Acidified dichromate
The elements with low electronegativities (_____) tend to form ions by losing electrons (_____). They can be called _____________ agents.
metals, oxidation & reducing
The strongest reducing agents are found in…
group 1
The elements with high electronegativities (_____) tend to form ions by gaining electrons (______). They can be called ____________ agents.
non-metals, reduction & oxidising
The strongest oxidising agents are found in…
group 7
Oxidising agents are widely employed to…
kill fungi and bacteria, bleaching stuff
Apart from electronegativity, how can you determine the ionic character of a compound
Ionic compounds will conduct, have higher mps and be soluble in water.
Acidified potassium dichromate use
Oxidising agent
Acidified potassium dichromate colour change
Orange > green when oxidised
(think of copper orange to green)
