Electrons, Bonding and Structure & Shapes Of Molecules And Ions Flashcards
Explain why ionic compounds have high melting and boiling points (2)
- Strong electrostatic attractions between oppositely charged ions.
- High temperature needed to provide sufficient energy to overcome the attractions.
Explain why ionic compounds dissolve in water (2)
- Polar water molecules are attracted towards ions on the surface of the ionic lattice. Water molecules bond to the ions, weakening and breaking them.
- Ions become surrounded by water molecules and break free from the lattice
Define: covalent bonding
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
Define: orbital
A region around the nucleus that can hold up to two electrons with opposite spins
Define: isoelectronic
The same number of electrons
State the maximum number of electrons that can be held in each of the first three shells of an atom. (3)
1st = 2
2nd = 8
3rd = 18
State how many orbitals there are in a p-subshell and how the electrons are arranged if the subshell is full (3)
- 3 atomic orbitals
- each orbital has 2 electrons
- with opposite spins
Explain why both G1 & G2 are known as s-block elements (1)
The outer electrons are s-subshell electrons for all
Explain the strength of the ionic bond in sodium chloride (2)
- strong electrostatic attraction
- b/w Na+ and Cl- ions
Explain why it’s easier to use aqueous MgF2 in a lab setting than the molten version (2)
- High melting point
- as strong electrostatic attraction b/w oppositely charged ions in all directions
Compare the binding in phosphorus trichloride and ammonia (4)
- both undergo covalent bonding
- phosphorus Atom and nitrogen atom are both central atoms
- each have 1 lone pair
- 3 shared pairs of electrons
Describe how the shape of the periodic table is linked to the electronic structure (6)
- elements in same period have same number of filled shells
- elements in same group have same number of valence electrons
- s-block includes G1 & G2 as it takes only 2 electrons to completely fill s-subshell
- p-block includes G3-0 as it takes 6 electrons to completely fill the p-subshell
- d-Block includes transition metals as it takes 10 electrons to completely fill d-subshell
- d-block begins on period 4 as d-orbitals have higher energy than 4s orbitals
Suggest why there are three possible p-subshells but only one possible s-subshell in an atom (3)
- s-orbitals are spherical so multiple subshells not possible
- p-orbitals are propeller shaped so 3 p-orbitals would not overlap significantly
Justify why hydrogen is positioned in the middle of the periodic table and not apart of G1 (3)
- very diff physical properties to G1 metals
- and chemical properties
- despite outer shell containing 1 s-subshell electron only
Explain why giant ionic structures have high melting points (2)
- strong electrostatic attraction between oppositely charged ions
- large amounts of energy required to overcome them
Explain why sodium bromide has a higher melting point than sodium and sodium iodide (6)
Stage 1:
- Na has metallic bonding & a giant structure
- there’s attraction b/w positive nucleus and delocalised electrons in Na
Stage 2:
- ionic bonding in NaBr & giant structure
- there’s attraction b/w + and - ions in NaBr
Stage 3:
- ionic bonds are stronger than metallic bonds
- stronger attraction b/w the + and - ions in NaBr than NaI
- since Br- ion is smaller than I- ion
Why is an arrow used to represent a
N ➡️ H bond? (1)
To show both electrons come from nitrogen
Suggest how methanol and methanethiol could be separated (1)
(Fractional) distillation
Define: ionic lattice (2)
- Repeating pattern
- of oppositely charged ions
State whether the following conduct electricity when solid or molten: (5)
- aluminium
- aluminium fluoride
- boron tribromide
Aluminium:
- conducts in solid and molten stated
- has delocalised electrons
Aluminium flouride:
- conducts when molten because it has mobile ions
- doesn’t conduct when solid (ions fixed in position in an ionic lattice)
Boron tribromide:
- does not conduct in solid and molten states (no mobile ions)
Explain how the structure and bonding in bromine account for its relatively low melting point (3)
- forces b/w molecules
- which are induced dipole-dipole forces
- are weak so overcome easily by increased kinetic energy
Predict the type of structure and bonding of SO2 and MgO & explain the difference in their melting points (4)
- MgO = giant ionic
- SO2 = simple molecule
- ionic bonds in MgO much stronger than intermolecular bonds in SO2
- ionic bonds in MgO require more energy to overcome
Describe the relative energies of the 2s orbitals and each of the three 2p orbitals in a nitrogen atom (2)
- p-orbitals have greater energy than
s-orbitals - three p-orbitals have equal energy
What are the 3 rules for filling electron orbitals? (3)
- Hund’s rule (each orbital must be singlely occupied before being paired up)
- Each orbital can hold up to 2 electrons with opposite spins
- Lowest energy orbitals must be filled first
Why is hyrogen H+
fills 1s orbital
