Unit 1-bonding, Structures & Properties Flashcards
What are atoms of elements
The building blocks which make up everything in the universe
What can atoms join together to make
Bonds
What happens when 2 or more atoms join together
They from a molecule
What happens when the atoms are the same
It’s a molecule of an element
How many atoms are diatomic atoms made up of
2
What are the 7 diatomic elements in the periodic table
hydrogen, chlorine, bromine, oxygen, fluorine, iodine, nitrogen
Why do atoms form bonds
To achieve the most stable outer electron arrangement- a full outer shell
What are covalent bonds
When 2 positive nuclei are held together by their common attraction for the shared pair of negative electrons
What are covalent bonds formed of
Between 2 non-metals (usually)
What kind of level of attraction do covalent bonds have
Extremely strong forces of attraction
How do atoms form bonds
Using the electrons in their outer most energy she
L
What do bonding diagrams do
They give a simplified picture of an atoms outer electrons
What do molecules exist in
3 dimensions
What does the shape of a simple covalent molecule depend on
The number and orientation of bonds around the central atom
What does the bond look like and its perspective when it’s a straight bond
A straight line, in the plane of the paper
What does the bond look like and its perspective when it’s a wedge bond
A door stopper, coming towards you
What does the bond look like and its perspective when it’s a dashed bond
Straight lines getting longer, going away from you
What do you call one bond
Linear
What do you call two bonds
Angular
What do you call 3 bods
Triganol pyramidal
What do you call 4 bonds
Tetrahedral
What do covalent substances form
Either discrete molecular or giant network structures
What are covalent molecular at room temp
Can be solids, liquids, or gases
What happens when a covalent molecular compound melts or boils
The weak intermolecular force is broken and the strong covalent bonds are left intact.
Do covalent molecular have high or low boiling pints
As there is less energy required they have lower melting and boiling points
What are covalent networks
They exist as giant network structures held together strong covalent bonds
Do covalent networks have high or low boiling points
As there is lots of energy required to break the strong covalent bonds there is a high melting and boiling points
What are examples of covalent networks
Carbon in the form of graphite and silicon dioxide
What state is covalent network at room temp
Solid
What does the chemical formula of a covalent molecular substance give
The number of atoms present in the molecule
What does the formula of a covalent network substance give
The simplest ratio of atoms in the substance
Different elements form what kinds of bonds
Different kinds of bonds
What is a valency
The ability of atoms to combine with other atoms
What does an atoms valency depend on
How many outer electrons it has
What does the compound name sometimes have at the start of
A prefix
What dumber does mono mean
1
What number does di mean
2
What number does tri mean
3
What number does tetra mean
4
What number does penta mean
5
What number does hexa mean
6
What number does hepta mean
7
What happens when atoms gain or lose electrons
Charged particles called ions are formed
What happens if an atom gains an electron
It becomes a negatively charged ion
What happens if an atom loses an electron
It becomes a positively charged ion
What happens when metals lose electrons
They become positively charged ions
What happens when non-metals gain electrons
They become negatively charged ions
What do atoms achieve when they form ions
The same arrangement as there nearest noble gas
What does ionic bonding occur between
A metal and a non metal
What does ionic bond mean
The electrostatic force of attraction between positive and negative ions
What is an ionic lattice
A giant arrangement of ions held together by electrostatic attraction (ie. ionic bonds)
What are in ionic lattices
Millions of ions held together in a lattice by ionic bonds
How much energy is required to break an ionic lattice
Lots of energy and as a result they have high melting and boiling points
What state are ionic compounds at room temp
Solid
What does the formula of an ionic compound give
The simplest ratio of ions in the substance
What is your charge on the ion if your in group 1
+
What is your charge on the ion if your in group 2
2+
What is your charge on the ion if your in group 3
3+
What is your charge on the ion if your in group 4
/
What is your charge on the ion if your in group 5
3-
What is your charge on the ion if your in group 6
2-
What is your charge on the ion if your in group 7
-
What is a group ion
An ion which contains more than one type of atom
What is electric current
A flow of charged particles
What are conductors of electricity
They allow an electric current to flow through them
What do non conductors of electricity do
They do not allow an electric current to flow through
Do metals conduct
Metal elements and carbon (in the form of graphite) are electrical conductors
do non metals conduct
Non metal elements are non-conductors of electricity
What happens to an outer electron of metals atoms
They are not attached to a particular atom and are free to move around. They are delocalised
Why do metals conduct electricity
Because there electrons are free to move around
What happens to the atoms in a covalent bond which means they can’t conduct electricity
They share a pair of electrons this means that the electrons are not free to move around and there is no conduction of electricity
Why can’t non metals conduct electricity
They do not have charged particles which can move and therefore they can’t conduct
What is the exception of non metals not conducting
Carbon (in the form of graphite)
What structure does graphite have
A layered covalent network structure
For carbon graphite how many electrons does each carbon atom use
3 electrons for bonding, the remaining electron is delocalised over the whole structure
Why can carbon graphite conduct
The electrons are free to move around between the layers , therefore it can conduct because electricity can flow through it
Do covalent compounds conduct and why
They do not conduct electricity as the electrons are not free to move
What state do ionic compounds do not conduct electricity in
The solid state. They conduct when dissolved in water or when molten
Why do ionic compounds not conduct in solid but 5hey do in liquid.
Because the ions are not free to move but when the ionic compounds dissolve in water the lattice breaks and the ions are free to move
What happens when you melt an ionic compounds
It breaks down the lattice and allows the ions to move
Are covalent molecular substances soluble
They are insoluble in water but mayo be soluble in other solvents
Do covalent network substances dissolve
They do not dissolve
Are ionic compounds soluble in water
They are soluble in water as they dissolve, the lattice structure break up allowing water molecules to surround the separated ions
Are ionic compounds soluble in covalent solvents
They tend to be insoluble in covalent solvents like ethanol
