2.2.1 + 2.2.2 Electrons Bonding And Structure (Dr C) Flashcards
What is the first sub shell
S-orbital
How many electrons can the s orbital hold
2
How many s orbitals are there in each shell
1
What is the second sub shell
P-orbital
How many p orbitals are there
3
How many electrons can the p orbitals hold in total
6
What is the shape of an s orbital
Spherical
What is the shape of a p orbital
Dumb-bell shaped (at right angles from each other-along the x,y and z axis)
What is the third sub shell (n=3)
D orbital
How many d orbitals are there
5
How many electrons can the d-orbital hold in total
10
What is the fourth sub shell called (n=4)
The f orbital
How many f orbitals are there
7
Max number of electrons a f orbital can hold
14
Max number of electrons in the first shell
2
Max number of electrons in the second shell
8
Max number of electrons in the third shell
18
Max number of electrons in the fourth shell
32
Why can we put two negative electrons in the same orbital
They have opposite spins (on a box diagram one arrow points upward and one downward)
What is the s block in the periodic table
The first 2 groups
What is the p block in the periodic table
Groups 3,4,5,6,7,0
What is the d block in the periodic table
The transition metals
What is ionisation energy?
The amount of energy that is required to remove an electron from the metals to make them a +ve ion
Definition of the first ionisation
Removal of 1 mol of electrons from 1mol of gaseous atoms to form 1 mol of gaseous 1+ ions
Why does the energy increase for each ionisation?
Each energy is larger than the one before because electrons are removed closer to the nucleus and experience more attraction from the positive nucleus. As each electron is removed there is less repulsion between electrons and each shell is drawn closer to the nucleus.
The greater the atomic radius…
The weaker the nuclear attraction experienced by outer shell electrons
The greater the nuclear charge…
The stronger the attractive four r experienced by outer electrons
What is electron shielding/screening?
Is the repulsion between electrons in different inner shells. Inner shell electrons repel outer shell electrons and block them from the nucleus
What is the first ionisation energy?
The amount of energy required to remove 1 mol of electrons from 1 mol of gaseous atoms to form 1 mol of gaseous 1+ ions
What is the first ionisation energy?
The amount of energy required to remove 1 mol of electrons from 1 mol of gaseous atoms to form 1 mol of gaseous 1+ ions
What is the octet rule
Atoms want 8 electrons in their outer shell
Compound meaning
A substance formed when two or more different elements chemically bonded together in a fixed ratio
Ionic bonding meaning
The strong electrostatic attraction between positive and negative ions
Giant ionic lattice meaning
Three dimensional structure of positive and negative ions that are strongly attracted in all directions
Molecule meaning
2 or more atoms held together by covalent bonds
Lone pair
An outer shell pair of electrons not involved in chemical bonding
Average bond enthalpy
A measurement of covalent bond strength
Covalent bond definition
A covalent bond is the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
Define ionic bonding
The electrostatic attraction between positive and negative ions
Give one example of an ionic ally bonded substance
NaCl (sodium chloride - salt)
Define covalent bonding
Electrostatic attraction between a shared pair of electrons and the nuclei
Define metallic bonding
Electrostatic attraction between the positive metal ions and the sea of delocalised electrons
Why do giant ionic lattices conduct electricity when liquid but not when solid
In a solid state the ions are in fixed positions and thus cannot move. When they are liquid state they are noble and thus can move freely and carry charge
Giant ionic lattices have high or low boiling point, why?
They have high melting and boiling points because a large amount of energy is required to overcome the strong forces of attraction (electrostatic bonds)
In what type of solvents do ionic lattices dissolve?
Polar solvents eg water
Why are ionic compounds solvable in water?
Water has a polar bond. Hydrogen atoms have a positive charge and oxygen atoms have a negative charge. These charges are able to attract charged ions.
What is it called when atoms are bonded by a singular pair of shared electrons?
Single bond
How many covalent bonds does carbon form?
4
How many covalent bonds does oxygen form?
2
What is a lone pair?
Electrons in the outer shell that are not involved in the bonding
What is formed when atoms share two pairs of electrons?
Double bond
What is formed when atoms share three pairs of electrons?
Triple bond
What is the average bond enthalpy?
Measure of average energy needed to break the bond(s)
What is a dative covalent bond?
A bond where both of the shared electrons are supplied by one atom
How are oxonium ions formed?
Firmed when acid is added to water, H3O+
What does expansion of octet mean?
When a bonded atom has more than eight electrons in its outer shell
What are the types of covalent structure?
-simple molecular lattice
-giant covalent lattice
Describe the bonding in simple molecular structures
Atoms within the same molecule are held by strong covalent bonds and different molecules are held by weak into molecular forces
Why do simple molecular structures have low melting and boiling points?
Small amount of energy is enough to overcome the intermolecular forces
Can simple molecular structures conduct electricity?
No, they are non-conductors
Why do simple molecular structures not conduct electricity?
They have no free charged particles to move around
Simple molecular structures dissolve in what type of solvent?
Non polar solvents
Give examples of giant covalent structures
Diamond
Graphite
Silicon dioxide, SiO2
List properties of giant covalent structures
-high melting and boiling points
-non conductors of electricity except graphite
-insolvable in polar and non polar solvents
How does graphite conduct electricity?
Delocalised electrons present between the layers are able to move freely carrying charge
Why do giant covalent structures have high melting and boiling points?
Strong covalent bonds within the molecules need to be broken, which requires a lot of energy
What does the shape of a molecule depend on?
Number of electron pairs in the outer shell and the number of these electrons which are bonded and loan pairs
What is the shape diagram and bond angle in a shape with two bonded pairs and zero lone pairs?
Linear 180°
What is the shape diagram and bond angle in a shape with three bonded pairs and zero lone pairs?
Trigonal planar 120°
What is the shape diagram and bond angle in a shape with four bonded pairs and zero lone pairs?
Tetrahedral 109.5 degrees
What is the shape diagram and bond angle in a shape with five bonded pairs and zero lone pairs?
Trigonal bipyramid 90° and 120°
What is the shape diagram and bond angle in a shape with six bonded pairs and zero lone pairs?
Octahedral 90°
What is the shape diagram and bond angle in a shape with three bonded pairs and one lone pairs?
Pyramidal 107°
What is the shape diagram and bond angle in a shape with two bonded pairs and two lone pairs?
Non linear 104.5°
By how many degrees does each lone pair reduce the bond angle?
2.5°
Define electronegativity
The ability of an atom to attract the pair of electrons (the electron density) in a covalent bond
In which direction of the periodic table does electronegativity increase?
Top right towards fluorine
What does it mean when the bond is non-polar?
The electrons in the bond are evenly distributed
What is the most electronegative element?
Fluorine
How is a polar bond formed?
Bonding atoms have different electronegativities
Why is H2O polar whereas CO2 is non polar?
CO2 is a symmetrical molecule so there is no overall dipole
What is meant by intermolecular force?
Attractive force between neighbouring molecules
What are the three types of intermolecular forces?
Hydrogen bonds,
permanent dipole dipole bonds
London forces
What is the strongest type of intermolecular force?
Hydrogen bonding
Describe permanent dipole dipole interactions
Some molecules with polar bonds have permanent dipoles
forces of attraction between those dipoles and those are neighbouring molecules
Describe London forces
London forces are caused by random movements of electrons.
This leads to instantaneous dipole
instantaneous dipole induces a dipole in nearby molecules
induced dipoles attract one another
Are London forces greater in smaller or large and molecules?
Larger due to more electrons
Does boiling point increase or decrease down the noble gas group? Why?
Boiling point increases because the number of electrons increases and hence the strength of the London forces also increases
What conditions are needed for hydrogen bonding to occur?
Because oxygen nitrogen and fluorine are highly electronegative, H nucleus is left exposed
strong force of attraction between the hydrogen nucleus and the lone pair of electrons on O,N or F
Why is ice less than liquid water?
In ice water molecules are arranged in orderly pattern it has an open lattice with hydrogen bonds
In water, the lattice is collapsed and the molecules are closer together
Why does water have a melting/boiling point higher than expected?
Hydrogen bonds are stronger than other intermolecular forces so extra strength is required to overcome the forces
What does the principal quantum number indicate?
The Shell occupied by the electrons
What is a shell?
A group of orbitals with the same principle quantum number
What is an orbital?
A region around the nucleus that can hold up to 2 electrons with opposite spins
What are the rules by which electrons are arranged in the shell?
-electrons are added one at a time
-lowest available energy level is filled first
-each energy level must be filled before the next one can fill
-Each orbital is filled singularly before pairing
-4s is filled before 3d
Why does 4S orbital fill before 3D orbital?
4S orbital has a lower energy energy than 3D before it is filled
Which electrons are lost when an atom becomes a positive ion?
Electrons in the highest energy levels
What does the principal quantum number indicate?
The shell occupied by the electrons
What is a shell?
A group of orbitals with the same principle quantum number
How are oxonium ions formed?
Formed when acid is added to water H3O+
