Module 2.2 Flashcards
What happens when atoms lose /gain electrons
They become ionised (positively if they gain, negatively if they lose)
How are ionising patterns used to tell the number of shells an atom has
Energy is applied to an atom, exciting an electron, so that it leaves a shell
Electrons in the same shell are excited at similar energy levels
Where there is a large increase in energy there is a new shell
Why is more energy needed each time to remove an electron from an atom
When you remove an electron from the outer shell there is a greater force (applied by the nucleus) on the remaining electrons, so more energy is needed
What is an electron shell
The energy level which an electron orbits the nucleus
What are orbitals
The direction / orbit an electron follows at its energy level
What are S orbitals
The first orbital in the shell
They are circular and hold 2 electrons
How many electrons can each orbital hold
2
What are P orbitals
There are 3 P orbitals which all move in a figure 8
Px - along the x axis
Py - along the y axis
Pz - along the z axis
Why is there 1 S orbital and 3 P orbitals in the 2nd shell
As they hold a total of 8 electrons
Write the orbitals for sodium (NA11)
1S2 /\ 2S2 2Px2 2Py2 2Pz2 /\ 3S1
1st number = shell
2nd number = number of electrons
In what order do the p orbitals fill
Each orbital must be half full before one can hold 2 electrons
Px then Py then Pz
Why does hydrogen share electrons with all elements (orbitals)
Hydrogen has one electron so a 1S1 orbital
All orbitals / elements want to have full shells and become neutral, so it shares this electron with another
for example 1 hydrogen would bond to 1 sodium
The electron can be shared to all orbitals
What is shorthand notation (Aufbau principle)
A notation used to shorten writing out all the orbitals of an atom
It uses a noble gas as the next orbital will always be an S orbital
E.G Rubidium
[Kr] 5S1
where Kr is Krypton
How many electrons (in total) do D orbitals contain
10 - so 5 individual orbitals
How many electrons (in total) do F orbitals contain
14 - so 7 individual orbitals
When do D orbitals first appear
shell 3
When do F orbitals first appear
shell 4
How many electrons are in shell:
1
2
3
4
5
1 = 2 electrons
2 = 8 electrons
3 = 18 electrons
4 = 32 electrons
5 = 32 electrons
In what order to the orbitals fill
1s - 2s - 2p - 3s -3p -4s -3d - 4p - 5s - 4d - 5p - 6s - 4f - 5d - 6p - 7s
Fills in a snake pattern, the shell bellows s orbital will fill before the previous shells d orbitals
1s
2s 2p
3s 3p 3d
4s 4p 4d 5f
5s 5p 5d 5f
etc………………..
What is the difference between an orbital and a subshell
A subshell is the pathway in a shell which an electron moves. (the number of electrons in a subshell depends on the subshell)
An orbital is a mathematical function that shows the wave like nature of an electron. (orbitals can only have 2 electrons)
How does the size of atoms change moving from metals to non metals
Moving from the left of the periodic table to the right the atomic radius decreases
Why does the atomic radius decreases moving towards the non metals
The number of protons in the nucleus increases, so the nucleus has a greater NUCLEAR ATTRACTION to each electron
Why does the ionization energy needed increase moving left to right in the periodic table
The electrons require more energy to be removed from the orbitals
except in group 3 and 6
Considering Period 2, why is the ionization energy of group 3 (boron) an anomaly
Boron requires less energy to remove an electron from its outer subshell compared to Beryllium
Be = 1s2
B= 1s2 1p1
It requires less energy to remove an electron from the unstable p orbital, than the complete s subshell.
Considering Period 2, why is the ionisation energy of group 6 (oxygen) an anomaly
Oxygen requires less energy to remove 1 electron from its outer subshell than Nitrogen
N = 1s2 1px1 1py1 1pz1
O = 1s2 1px2 1py1 1pz1
IT requires less energy to remove an electron from the unstable 1px2 orbital in oxygen that to remove 1 electron from the half filled stable p subshell in nitrogen
When are subshells stable
When they are fully filled
When they are half filled (1 electron in each orbital)
Why does it require more energy to remove electrons from stable subshells than unstable subshells (with 1 additional electron)
Orbitals in stable subshells want to remain stable
Orbitals in unstable subshells of +1 electrons want to lose that electron to become stable.
As they want to lose the electron it requires less energy
What is charge density
The ratio of an ions charge to its volume
Which has a greater charge density Sodium or aluminum ions
Na + is in group 1
Al 3+ is in group 3
Aluminum has a smaller atomic radius and a greater charge, so its charge density is greater
How does the force of attraction between ions change with charge density
The greater the charge density the greater an ions electrostatic force of attraction
How do metals and non metals bond
They form ionic bonds
Metals donate electrons to have a full outer shell
Non-metals receive electrons to have a full outer shell
This makes the atoms oppositely charged so they attract each other
What are the general properties of ionic compounds
They have a giant structure - so they also have a high melting and boiling point
They can conduct electricity when dissolved or molten (as they contain charged particles - the ions)
They are soluble in polar solvents
What is the structure of a giant ionic lattice
Each ion is surrounded by an oppositly charged ion
The ions attract each other forming a giant ionic lattice
What determines the melting and boiling point in ionic compunds
The stronger the electrostatic force of attraction between ions the higher the melting / boiling point will be, as more energy is needed to break the ionic lattice
The strength of the attraction is determined by the ions charge density
Why cant ionic compounds conduct electricity when solid, but can when molten / dissolved
When solid, the ions are held in a fixed position and cannot move
When molten or dissolved the solid lattice breaks down, and ions can move
As the ions can move they can conduct electricity
What substances can ionic lattices dissolve in
Polar substances such as water
how do ionic lattices dissolve in water
Water surrounds the ionic lattice, and it begins to break down
The partially positive hydrogen bonds to the negative ion
The partially negative oxygen binds to the positive ion
What is a covalent bond
A bond formed when two non-metals share electrons
How are electrons shared in covalent bonds
The negative electrons are attracted to the nuclei of both atoms
The attraction of these electrons overcomes the repulsion force between the two positive nuclei
This forms a covalent bond where electrons are shared
How are covalent bonds drawn
Using dot and cross diagrams
Only the outer shell is drawn
The shared electrons are drawn in the overlapping space between the two electrons
What is a single bond
The covalent bond where only 1 pair of electrons are shared
What are lone pairs
A concentrated space / region of negative charge around an atom
2 electrons that are not used in bonding form a lone pair
What orbital is most commonly a lone pair in covalent bonding
The s orbital
This is because it is typically full, so electrons do not need to be shared with it in order to make the orbital stable
How are double bonds (covalent) formed
When the atoms share 2 pairs of electrons
How are triple bonds (covalent) formed
When atoms share 3 pairs of electrons
What type of reaction is bond breaking
exothermic
Which type of covalent bonds have the highest average bond enthlapy
Triple bonds will require a greater change in enthlapy to break than double or single bond
What is Dative covalent bonding
A bond formed where one atom provides both of the shared electrons in a covalent bond
How is a dative bond written
A (arrow) B
The direction of the arrow shows the direction the pair of electrons are donated
What type of atoms can form dative bonds
Dative bonds form between an atom with at least one lone pair and an atom (typically a positive ion) that has an electronic configuration of an empty orbital
How many covalent bonds can an atom form
- All unpaired electrons can pair up between atoms
- The maximum number of atoms that can pair up is equivelent to the number of electrons in the outer shell
What is an octet
a full outer shell
What is the octet rule
The octet rule states that:
All atoms prefer to have 8 electrons in their outer (valence) shell. This give them a stable electronic configuration
What are valence electrons
Electrons in an outer shell
Why does expansion of the octet occur
Moving down the periodic table, more of the outer shell electrons are able to take part in bonding
elements from group 5 to group 7 (g15 to g17) can expand their octet
Why do some atoms not complete their octet in covalent bonding
Atoms such as Boron do not have enough unpaired electrons
They have 3 electrons in an outer shell, so can have a total of 6 electrons once paired
How many covalent bonds can a group 5 element form
3 or 5 covalent bonds
How many covalent bonds can a group 6 element form
2, 4 or 6 covalent bonds
How many covalent bonds can a group 7 element form
1, 3, 5 or 7 covalent bonds
What are the two types of covalent structure
Simple molecular lattice
Giant covalent lattice
What are simple molecular lattices and their properties
MAde from small simple molecules such as H2O
The atoms in each molecule are held together by covalent bonds
The different molecules are held together by weak intermolecular forces
They have low melting and boiling points (weak intermolecular forces)
They dont conduct electricity
They are soluble in non-polar substances
Why are simple molecular structures / lattices soluble in non-polar solvents
Weak london forces can form between covalent molecules and non-polar solvents
This causes the molecular lattice to break down, dissolving the substance
What are giant covalent lattices and their properties
Lage repeating structures such as diamond - where there are covalent bonds between all atoms
They have high melting and boiling points (due to strong covalent bonds)
They cannot conduct electricity as there are no free charged particles (except in graphite)
They are completely insoluble as the covalent bonds in the lattice are too strong to be broken by polar or non-polar substances
What types of replusion are there between atoms that are covalently bonded
Bonding pair - bonding pair repulsions
If lone pairs are present:
Lone pair - bonding pair repulsion
Lone pair - lone pair repulsion
Bonding pair repulsions are the weakest
Why are there bonding pair repulsions in covalent bonds *******
When sharing electrons, the atoms become charged and repel each other
The share of electrons also repel each other
How do lone pairs repel bonding atoms in covalent bonds
They repel atoms downwards giving them a 3D structure
How many bonds / what is the bond angle in a linear(1) shaped covalent bond
There is 1 covalent bond (so there is no bond angle)
How many bonds / what is the bond angle in a linear(2) shaped covalent bond
There are 2 covalent bonds
There is a 180 bonding angle between bonded atoms
How many bonds / what is the bond angle in a trigonal planar shaped covalent bond
There are 3 covalent bonds
There is a 120 bonding angle between bonded atoms
How many bonds / what is the bond angle in a tetrahedral shaped covalent bond
There are 4 covalent bonds formed
There is a 109.5 bonding angle between bondinded atoms
How many bonds / what is the bond angle in a trigonal bipyramid shaped covalent bond
There are 5 covalent bonds
There is a 90 bonding angle between the bonded atoms in the plane
There is a 120 bonding angle between bonded angles coming out of the plane (towards and away)
How many bonds / what is the bond angle in a octahedral shaped covalent bond
There are 6 covalent bonds
There is a 90 bond angle between the bond in the plane and the bond coming out of the plane
How many bonds / what is the bond angle in a pyramidal shaped covalent bond
(And lone pairs)
3 covalent bonds
1 lone pair
107° between each bonding pair
How many bonds / what is the bond angle in a non-linear shaped covalent bond
(And how many lone pairs)
2 covalent bonds
2 lone pairs
104.5° bonding angle
When drawring covalent bonds what does the coloured in ‘wedge’mean
The bond is coming out of the plane (towards you)
When drawring covalent bonds what does the dotted ‘wedge’mean
The bond is going out of the plane (away from you)
What is electronegativity
The ability of a non-metal in a covalent bond to draw electrons to itself
What atom has the greatest electronegativity
Fluorine
What is the general trend of electronegativity
Moving up the periodic table and to the left, elements become more electronegative
What is the general trend of electronegativity
Moving up the periodic table and to the left, elements become more electronegative
What is a polar covalent bond
When the bonding atoms are different, one will have a greater electronegativity
THE BONDING PAIR of electrons are attracted more to the more electronegative element
This creates a small charge difference
1 atom has a partially positive charge
1 atom has a partially negative charge
How do non polar molecules contain polar bonds
If an atom is symmetrical the dipoles can cancel out (as they act in different directions)
This makes the atom non polar
What is a permanent dipole
A small charge difference across a bond (due to the electronegativity of atoms)
What are van der Waal forces
Intermolecular forces including:
London forces
Permanent polarity (due to electronegativity)
Hydrogen bonds
What is permanent polarity
A type of intermolecular force where one atom in a covalent bond is partially negative, and the other is partially negative
(Due to electronegativity)
What are london forces
An intermolecular force caused by the constant and random movement of electrons in an atoms shell
How do london forces form
Electrons are constantly moving around an atom / molecule
At any time, one side might contain more electrons than the other (making it partially negative)
This creates an instantaneous dipole across the molecule
The instantaneous dipole induces a dipole in the neighbouring molecule (which then induces more dipoles)
These induced dipoles attract each other creating weak intermolecular forces known as London Forces
Are london forces stronger or weaker when there are more electrons
The more electrons there are, the larger the induced dipole, the larger the attractive force between molecules
What are hydrogen bonds
The strongest intermolecular forces.
They occur in molecules containing
O-H
N-H
F-H
Hydrogen bonds occur between molecules which contain these bonds
Why are hydrogen bonds the strongest intermolecular force
Oxygen, nitrogen and fluorine are very electronegative elements
This means elements with these bonds have strong polar dipoles
How do hydrogen bonds affect the properties of water
It causes water to have a higher boiling point than expected
It causes water to be less dense in its solid state
Why is ice less dense than water
When ice forms water molecules arrange in an orderly pattern, allowing hydrogen bonds to form
This creates an open lattice (with hydrogen bonds holding the molecules apart)
Due to the empty space created, ice is less dense than watet
What are ionic bonds
Bonds formed by Electrostatic attraction between positive and negative ions
Describe the structure of water
Water is made of a central Oxygen covalently bonded to two hydrogen atoms
The oxygen is partially negative and the hydrogen is partially positive
The oxygen has two lone pairs
It forms a shape with a 104.5° bonding angle as there is lone pair - lone pair repulsion, bonding pair - bonding pair repulsion and lone pair - bonding pair repulsion, where the lone pairs repel more than the bomding pairs
What bond is in N2
A covalent triple bond
