IB Chemistry HL

What property generally decreases across a period?

Atomic radius

What property increases down group 1?

Reactivity

Define the term first ionisation energy

The amount of energy required to remove one mole of electrons from one mole of an atom in a gaseous state

Why is the first ionisation energy of magnesium is higher than that of sodium?

Greater positive charge on nucleus/greater number of protons.

Greater attraction by Mg nucleus for electrons

Small atomic radius

Sodium oxide + water?

Na2O(s) + H2O(l) \=\> 2NaOH(aq)

Basic

Sodium trioxide + water?

SO3(l) + H2O(l) \=\> H2SO4(aq)

Acidic

Distinguish between the terms group and period in terms of electron arrangement

Group: number of outershell electrons

Period: number of occupied shells

What statement about elements in group 7 is correct?

Cl- with oxidize I-

Which electron transitions are responsible for the colours of transition metal compounds?

Between d orbitals

Which change explains why the boiling points of the halogens increase as their molecular masses increase?

The intermolecular attraction due to temporarily induced dipoles increases.E

Examples of ligands?

Cl-, NH3, H2O

Which metal nitrate solution is coloured?

Ni (NO3)2 (aq)

Explain what the square brackets around the species represent?

It is a complex ion which a delocalized charge

Explain why the [Cu(H2O)6]2+ ion is coloured and why the [CuCl4]2- ion has a different colour?

Colour is due to energy being absorbed when electrons are promote within the split d orbital.

There is also a change in ligand/coordination number which changes the amount the d orbitals are split

P4O10 + 6H2O \=\> ?

4H3PO4

What happens across period three?

Electronegativity of elements increases

Atomic radii decreases

Reaction of sodium and water?

2Na(S) + 2H2O(l) \=\> 2NaOH(aq) + H2(g)

Why is the reaction between rubidium and water more vigorous than that between sodium and water

Rb is more reactive because electrons are lost further from nucleus so less tightly held.

Rb electron is in 5th energy level and Na is less reactive electron in 3rd energy level

Describe what you will see if chlorine gas is bubbled through a solution of potassium iodide?

Solution becomes yellow/orange/darker because chlorine is more reactive than iodine

Iodine is formedE

Describe what you will see if chlorine gas is bubbled through a solution of potassium fluroide?

No change happens because fluorine is more reactive than chlorine

Why does the melting points of elements decrease down group 1 and increase down group 7?

G1: The Metallic bondings get weaker and the atomic radii increases

G7: Increase atomic number of halogen molecules

London dispersion forces increase

Why is Cu a transition metal and scandium is not?

Cu has d electrons

Cu compounds are coloured and has more than one oxidation state

Difference between AlCl3 and Al2O3?

AlCl3 is covalent simple molecular and Al2O3 is ionic giant ionic lattice

What property decreases down group 7 in the periodic table?

Electronegativity

Explain the increase in the melting point from sodium to aluminium

The Ions become more positive and the atomic radii decreases and therefore there is a greater attraction for delocalised sea of electrons

About noble gases?

Do not form bonds easily, already have a stable octet and cannot attract more electrons

Why does electronegativity increase across period 3?

Increasing atomic number, atomic radius decreases and shielding stays the same

Why is the ionization energy of Al lower than Mg?

Outer electron in Al is in p orbital which is higher and the e- are further from the nucleus

Explain the origin of colours in transition metals

D orbitals are split (two sets of different energies).

The frequencies of visible light absorbed by electrons moving from lower to higher d levels. Colour due to remaining frequencies colour transmitted

How is the bond formed between Cu2+ and NH3

NH3 ligand donates electron pairs to Cu2+, they replace the H2O ligands around Cu2+ ion and form dative covalent bonds

Magnesium oxide + water?

MgO + H2O \=\> Mg(OH)2

What is periodicity?

The repeating pattern of (physical and chemical) properties.

Which compound is used as a catalyst in the contact process?

V2O5

factors that affect crystal field splitting energy

metal ion identity and oxidation state, nature of ligands and geometry of complex ion.

What is meant by the term "paramagnetic

When the element has subshell that is not filled, which allows it to be affected by magnetic fields. Examples are Li and N

State 2 characteristics of transition elements.

catalysts, variable oxidation state, magnetic properties, form coloured ions and complex ions

Explain why Cr is malleable?

Delocalized electrons allow the layers/rows of cations Cr+3 ions to slide past each other (without) disrupting the metallic bonding

Explain why many compounds of d-block (transition) elements are colored

presence of unpaired electronsthe d orbitals are split into two energy levelselectrons move between these energy levels. electrons can absorb energy from light of visible wavelength

Which process is responsible for the colour of a transition metal complex?

The absorption of light when electrons move between different d orbitals

first electron affinity

The energy released (exothermic) when 1 mole of gaseous atoms each acquire an electron to form 1 mole of gaseous 1- ions. Follows the same trend as ionisation energy for the same reasons.

Which electron affinity reactions are exothermic, and which are endothermic. Why

The first is always exothermic due to the attraction to the positive nucleus.The second and third are endothermic due to the repulsion from the negative ion.