Studied by 12 people
Where are the metals and metalloids found in the periodic table
The metals are found on the left hand side in the s block and d block
The metalloids are found on the right hand side between the metals and non metals
What is the nuclear charge
given by atomic number, increases by one with every successive element
What is the effective nuclear charge
The net positive charge experienced by an electron in an atom. It is determined by subtracting the number of shielding electrons from the total number of protons in the nucleus. It is less than the full nuclear charge.
How does effective nuclear charge change across a period and down a group
Across a period the effective nuclear charge decreases as one proton is added but no inner electrons, reducing shielding.
Down a group the effective nuclear charge decreases due to increased shielding by inner electrons as more shells are added.
How does atomic radii change across a period and down a group
Across a period the atomic radii decreases as the nuclear charge increases and electrostatic attraction pulls the electrons closer, reducing radii.
Down a group the atomic radii increases due to a larger number of occupied shells.
What are the trends in ionic radii
Positive ions are smaller then their original atom due to losing the outer shell
Negative ions are larger then their original atom due to gaining electrons, which increases electron repulsion so the electrons move further apart and increase the radii
How does ionisation energy change across a period and down a group
Increase across a period due to increased effective nuclear charge so electrons are harder to remove
Decrease down a group due to increased atomic radii so electrons are at a further distance from the nucleus, so they are easier to remove
What is electron affinity
The energy change when one mole of electrons is added to one mole of gaseous atoms to form one mole of gaseous ions. It measures how atoms accept electrons.
How are the first and second electron affinities different
The first electron affinity is exothermic, The second is endothermic.
How do different groups have differing electron affinities
Group 17 have the highest electron affinity as they have incomplete outer levels and a high nuclear charge
Group 1 have the lowest electron affinity as they only have one electron in the outer shell and the lowest nuclear charge.
What is electronegativity
The measure of an atom's ability to attract electrons in a covalent bond, indicating its relative strength in pulling shared electrons towards itself.
How does electronegativity change across a period and down a group.
Increases across a period due to increasing nuclear charge, therefore a higher electrostatic attraction between the nucleus and electrons
Decrease down a group as the bonding electrons get further away from the nucleus due to added shells, reducing electrostatic forces.
How does the ionisation energies and electronegativities differ in metals and non metals
Metals have lower ionisation energies and electronegativities
How does melting points change down a group in group 1 and 17
Group 1 melting points decrease down a group due to the metallic structure, the ions get bigger as you go down a group which reduces forces of attraction.
Group 17 melting points increase down a group due to increased number of electrons which hold together the molecular structure due to London Dispersion forces
What are the features of group 18: the Noble Gases
They are the least reactive elements as they have a full outer shell
They are colourless
They are monatomic
They do not form ions as they have a stable octet
What are the features of Group 1: The Alkali Metals
Very reactive
Form ionic compounds with non metals
Low density
Conducts electricity and heat
Form single charged ions
Low ionisation energy
Reacts with water to produce hydrogen and a metal hydroxide, reacts with halogens to produce halides,
What are the features of Group 17: The Halogens
They are coloured
Very reactive, reactivity decreases down the group
React with Group 1 metals to form halides
They also engage in displacement reactions, the more reactive halogen replaces the less reactive in the reaction.
What are the physical properties of the transition metals
High conductivity of heat and electricity
High melting point
Malleable
Ductile
Iron, Cobalt and Nickel are ferromagnetic
What are the chemical properties of transition metals
Form compounds with more than one oxidation number
Form a variety of complex ions
Form coloured compounds
Acts as catalysts
Why is zinc not a transition metal
It does not follow the chemical properties of a transition metal, this is because in its atom and in 2+ state, it has a full d shell
What are the common oxidation states of transition metals
The 3+ ion is the most stable for elements scandium to chromium
The 2+ ion is the most stable for the later elements due to increased nuclear charge making it harder to remove an electron
What happens with oxidation states above 3+
They show covalent character
What compounds are used as oxidising agents
Compounds with higher oxidation states
What are complex ions and how are they formed
When transition metal ions are in solution due to their high charge density they attract water molecules. These form co-ordinate bonds with the positive ion to form a complex ion.
In general a complex ion is formed when the central ion is surrounded by molecules/ions attached via co-ordinate bonds.
What are the species surrounding the central ion in a complex ion called
ligands
What is the co-ordination number
The number of co-ordinate bonds from the ligands to the central ion.
What are polydentate ligands
when species have more than one available lone pair to form a coordinate bond with the central ion.
What is a heterogeneous catalyst
When the catalyst is in a different state to the reactants. This is useful in industry as the catalyst can be easily removed by filtration after use.
What are homogenous catalysts
When the catalyst is in the same state to the reactants. As these catalysts mix well with the reactants they work well in the mild conditions of the human body.
What is the difference between diamagnetism, paramagnetism and ferromagnetism
Diamagnetism = property of all materials, produces very weak opposition to an applied magnetic field
Paramagnetism = when substances have paired electrons, the force is stronger than diamagnetism. Produces magnetism proportional to the applied field in the same direction
Ferromagnetism = the largest effect, can produce magnetism greater than the applied field (only Iron, Nickel and Cobalt)
Why are certain compounds coloured
Because they absorb light of a certain colour, and emit/reflect the complementary colour (opposite on the colour wheel).
Why do transition metals absorb light
Due to a ligands electric field from the lone pair of electrons, the d orbital is split into 2 sub levels. When light passes through these compounds one 3d electron is excited to the higher sub level, a photon of light is absorbed and the complementary colour light is emitted when the electron falls back.
What affects the colour of the transition metal complex
The nuclear charge of the central ion, this increases electrostatic attraction with the electrons and make the ligands interact more effectively due to stronger co-ordinate bonds
The geometry and orientation of the ligands and d orbitals
The number of d electrons and oxidation state of the central ion, depends on electron repulsion.
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