ionic/covalent/metallic/ + Electrolysis P1 Flashcards
why arw group 3, group 4 and group 5 not usually ions
Because they would have to gain 5,4 or 3 electrons which would require a lot of energy
how is an ion formed
by loss or gain of electrons
When an atom becomes an ion what do you add to the end of the word
IDE
Why are metals positively charged(talk about prot aswell)
Because they lose electrons. So have more protons than electrons
What is an ionic bond
An electrostatic attraction between positive and negative ions
Explain how ionic bonding takes places
Electrons from the metal are transferred to the outer shell of the non metal,
because of strong electrostatic forces of attraction
between the oppositely charged ions.
both have a full outer shell
Are ionic compounds neutral or not?
Ionic compounds are neutral
Which groups have noble gas configuration [2,8] [2,8,8]
1,2,6,7
What does isoelectronic mean
Has the same number of electrons o same electronic configuration
What is an empirical formula
Simplest whole number ratio of atoms
What is a lattice
A regular arrangement of particles
What kind of lattice do ionic compounds have
giant ionic lattice
why does a magnesium oxide (Mg2+, O2-) have greater forces of attraction than Sodium Chloride (Na-, CL-)
Because ions in magnesium oxide are attracting 2+ and 2-, making thr electrostatic attractions stronger than (1+,1-)
Explain the arrangement of ions in an ionic lattice
Ions are arranged in a regular, repeating lattice
Why do ionic compounds have high melting and boiling points
-they have strong electrostatic forces of attraction between the oppositely charged ions so a lot of energy is required to break these forces.
In which way do forces of electrostatic attraction act in an ionic lattice?
Strong forces of electrostatic attraction act in all directions
Why do ionic compounds tend to be crystalline
Due to the regular arrangement of ions in the lattice
Why does magnesium oxide appear as a white powder
Because the crystals are too small to be seen with the naked eye
Why are ionic lattices brittle
Because any small distortion can cause ions of the same charge to become alongside each other.Like charges repels the crystal splits itself apart
What substance are ionic compounds soluble in
Soluble in water
what substances are ionic compounds insoluble in, (give 2 examples)
Organic solvents
Such as ethanol
Or HYDROCARBONS such as HEXANE in PETROL
Why do ionic substances not conduct electricity when solid
Because the IONS are in fixed positions
in the giant ionic lattice
And are not free to move around
Why do ionic substances conduct electricty once molten
Because the ions are no longer in fixed positions and are free to move around
What two things can you do to an ionic compound to make it conduct electricity
Make it molten (melted)
Make it an aqueous solution (dissolved in water)
What can ionic compounds contain which is an exception to them always consisting of a metal
Ammonium ions
What is an ion
An atom or group of atoms that carries a charge
What is ionic bonding
When there are electrons forces of attraction between positively charge and negatively charged ions
holding them together
draw a dot an cross diagram of lithium oxide
(Answer should have two lithium atoms on either side of an oxygen atom)
Draw dot and cross diagram of Calcium Bromide
(Two atoms of bromide on either side of an atom of calcium)
(Each Bromide should have 7 of its own electrons + one calcium)
(Calcium should have full outer shell)
Work out the Formula of magnesium sulfate
MgSO4
Work out the formula of calcium nitrate
Ca(NO3)2
Work out the formula of sodium sulfate
Na2SO4
Formula of ammonium Sulfide
(NH4)2S
How is a covalent bond formed
When two non metal atoms share electrons
What holds covalent bonds together
Strong electrostatic forces of attraction between positive nuclei of each atom
and negatively charged shared electrons
After covalent bonding, is a hydrogen molecule the same as a noble gas because it has the same electronic configuration?
No, because a hydrogen atom still has the same number of protons in the nuclei
Explain How does an atom become more stable(in terms of bonds and energy)
If the atom makes more bonds than more energy is released so it will be much more stable
What does energy release between atoms do to the bond
Makes it more stable
Formula for ammonia
NH3
Formula for Methane
CH4
Formula of ETHANE
C2H6
Draw a stick diagram of nitrogen
N- - - N
(Triple bond)
Draw a stick diagram for ethene
C2H4 so
Two central carbon atoms with two bonds
2 hydrogen atoms surrounded by each carbon with single bonds
Formula for ETHENE
C2H4
So two central carbon atoms with a double bond
And then two hydrogen atoms surrounding each carbon atom with a single bond
Draw a dot and cross diagram for Chloroethene(CH2CHCL)
two central carbon atoms
With 2 hydrogen atoms around one carbon
And 1 hydrogen atom and one Cl atom around one carbon
What is broken when you boil water
Weak intermolecular forces
What holds a single water molecule together
Strong covalent bonds
Why do substances with simple molecular structure have low melting and boiling points?
Because there are weak INTERMOLECULAR forces of attraction between the molecules which do not need a lot of energy to break
Are covalent bonds strong or weak
Strong
As you go down the group of halogens, why do you need to supply more energy to break the weak intermolecular forces of attraction?
Because the molecular mass increases so the intermolecular forces of attraction between the molecules become stronger
Why do covalent molecules not conduct electricity (2)
Because the molecules do not have an overall charge,
And because all electrons are held tightly by covalent bonds so can not move around
What does a molecule consist of
Consists of a fixed number of atoms
joined by covalent bonds
Why is diamond not a molecule
Because the number of atoms are variable and are not fixed
Why does diamond have a high melting point
Because of the strong covalent bonds which extend throughout the structure and require a lot of energy to break
Give 3 substances that exist with a giant molecular structure
Silicon dioxide, diamond, graphite
Why does diamond form a tetrahedron
Carbon has 4 atoms in its outershell so creates 4 bonds
Why does diamond not conduct electricity
Each carbon atom is bonded to four other carbon atoms by four strong covalent bonds, leaving no delocalized electrons or no free ions
Why does graphite conduct electricty
One carbon is joined to three other carbon atoms
so it has one delocalized electron
which is able to move between the layers and conduct a charge
Why is graphite soft
Because the attractions between the layers are weak
and not much energy is needed to overcome them
And so they are able to Slide Over each other
Does graphite have a high or low melting point and explain why
High melting and boiling point
because there are strong covalent bonds between the atoms IN EACH SEPEARTE LAYER
which require a lot of energy to break
What is an allotrope
Different forms of the same element
Describe the structure of c60 fullerene
Simple molecular structure
So consists of molecules with weak intermolecular forces of attraction between them
Where each molecule consists of 60 carbon atoms
What kind of melting point does fullerene have and why
Low melting and boiling point because of simple molecular structure
So weak intermolecular forces of attraction between the molecules
Name three allotropes of carbon
Diamond, graphite and fullerene
How many bonds does C60 fullerene create
3
Why can C60 fullerene not conduct electricity even though it only has three bonds
Because the fourth electron in one atom can only move around one molecule and is not able to jump to other molecules
How is a metallic bond formed(4)
When metals atoms bond, their outer electrons become detached
Causing a sea of electrons
The atoms become positively charged ions
And it is the electrostatic forces of attraction between the positively charged ions and the electrons that keep the metallic bond
Why do metals conduct electricity (in terms of metallic bonding)
Because they have delocalized ELECTRONS which are free to move
What is metallic bonding
It is the electrostatic forces of attraction between each positive ion and the sea of delocalized electrons
What type of structure do metals have
Giant structure
Why are metals malleable
Because the layers of positive ions are able to slide over each other
What two substances are exceptions of electrolysis of covalent compounds
Ammonia solution and hydrogen chloride(because hydrogen chloride gas dissolves in water to form hydrochloric acid
Why can covalent compounds not be used in electrolysis
Because their electrons are tightly packed and are not able to move
and because their molecules do not have an overall charge
What is the positive electrode called
Anode
What is the name of a positive ion
Cation
What is the name of a negative ion
Anion
What is the name of the negative electrode
Cathode
What is electrolysis
A chemical change caused by passing an electric current through a compound which is either molten or in solution
What are the electrodes usually made of and why
Carbon
because it conducts electricity well
and is also inert
if a solution is insoluble, will you melt it or dissolve it in water for electrolysis
Melt it
What is another substance used before aluminum oxide can be an electrolyte and what does it do
Mix it with molten cryolite to lower melting point of aluminum
What are three examples of electrolyte
Molten salts
Aqueous solutions of ionic compounds
Molten metals
If you electrolyse a molten ionic compound, which substance will form at the cathode and why
The metal because it has a positive charge
What state must an ionic compound be in if it is to be used as an electrolyte
Must be molten or dissolved
When labeling an electrolysis diagram, what 4 things should you include
-DC power supply
-inert anode(positive electrode)
-inert cathode (negative electrode)
-electrolyte
Write the half equation for copper sulfate at the cathode
Cu(2+) + 2e—— Cu
If you are observing hydroxide being formed in electrolysis, what will you observe
Bubbling around the electrode
If you are observing chlorine being formed at the electrode, what will you observe?
Green/yellowish bubbling
How is carbon dioxide formed as a waste gas in electrolysis of molten aluminum oxide
When oxide goes to the anode, oxygen gas is formed
Because it reacts with the carbon electrode to form carbon dioxide
2 properties of aluminum that make it suitable for food and drink
Malleable
Low density
During electrolysis of aluminum oxide, apart from oxygen, what else is formed at the anode and why
Carbon dioxide
Because the oxygen reacts with the carbon of the electrode
Write the ionic hard equation of the equation at the anode of aluminum oxide
2O2+ —-) O2 + 4e
(Oxygen is being oxidized
And because it is a diatonic molecule the number of electrons needs to be doubled)
(So would start as O2- —-) O2 + e-
Then you would need to balance the oxygen on left and on right so would become 2O2—-) O2 + e-
And then would need to balance the charges so 2O2- —-) O2 + 4e-
During electrolysis of aluminum oxide, why must the anode be constantly replaced
Because the anode is being oxidized
As the carbon form the anode reacts with the oxygen to form carbon dioxide
Suggest why the melting point of silicon dioxide is higher than the melting point of sodium chloride
Because the covalent bonding in silicon dioxide is higher than the ionic bonding of sodium chloride
Can diamond conduct electricity when molten
No
Describe the structure and bonding in the group three metal indium
Has a metallic lattice structure
Held together by strong electrostatic forces of attraction
Between the positively charged ions
And delocalized electrons
Why would you have H+ and OH- ions in an aqeous solution
Because water in solutions splits up into its ions
Describe the structure of an ionic substance, and then the structure of a giant covalent substance
Ionic:
-arranged in a giant ionic lattice
-ions are tightly packed and regularly arranged
-repeating pattern of positive and negative ions
Giant covalent:
-arranged in giant lattice structure
-where the number of atoms is variable
-repeats in 3 dimensions
Why is diamond hard
Because of the rigid tetrahedral structure
Which of the allotropes of carbon can conduct electricity, and which can’t,
graphite is the only one that can
Fullerene and diamond cant
Describe the structure of metallic substances
Giant metallic attic structure
So ions are in variable amounts
And held together between positively charged ions and delocalized electrons
Give the names of two compounds that can be split up using the molten way of electrolysis
Aluminum oxide
Lead bromide
During the electrolysis of aluminum oxide, state what deposits at the bottom
Molten aluminum
In the electrolysis of lead bromide, state two observations made and explain what they are
Grey solid deposits at the bottom which is lead
Bubbling at the anode because bromide gas formed
Why do you need rules to determine what forms at what electrode, when talking about aqeous solutions
Because water in soltuion splits up into its ions
Therefore you have four different ions to choose from
If using an aqueous solution in electrolysis, and turns out that hydroxide ions will be discharged at the anode, what are the two products formed
And state the equation
Oxygen and water
4OH- ——-) 2H2O + O2 + 4e-
