1.6- The Periodic Table Flashcards
(a)
Structure
Elements are arranged in order of increasing atomic number. They are positioned in vertical groups and horizontal periods.
(b)
electronic structures of the elements and their relation to their position in the s-, p- and d blocks of the Periodic Table
Divided into s, p, d and f blocks.
The block denotes the subshell the elements’ valence electrons are in.
(c)
Oxidation and reduction
Oxidation is loss of electrons and reduction is gain of electrons.
(c)
Oxidising agent
An oxidising agent is a species that accepts electrons; it becomes
reduced itself in the process.
(c)
Reducing agent
A reducing agent is a species that donates electrons; it becomes
oxidised itself in the process.
(c)
Redox reaction
If the oxidation number increases, the species is oxidised; if it
decreases, the species is reduced.
(d)
Trends in ionisation energy
Ionisation energy generally increases across a period due to increasing nuclear charge in the same energy level.
However, it decreases between Group 2 and Group 3 due to shielding by s-electrons and between Group 5 and Group 6 due to electron-electron repulsion in a p-orbital.
Down a group, ionisation energy decreases as increased shielding from inner electrons reduces nuclear attraction on the outer electron.
(d)
Trends in melting temperature
Melting and boiling points increase from the first to the fourth element due to strong metallic or giant covalent bonding. There is then a sharp decrease at the fifth element as bonding changes to simple molecular covalent, followed by a gradual decrease to the eighth element due to weaker intermolecular forces.
(d)
Trends in electronegativity
Electronegativity increases across a period because there is an
increase in nuclear charge, but the bonding electrons are always
shielded by the same inner electrons.
(e)
reaction of Group 2 elements with oxygen
2X + O2 ⟶ 2XO
X is Group 2 element
(e)
reaction of Group 2 elements with water/steam
X + 2H2O ⟶ X(OH)2 + H2
X is the Group 2 element.
(f)
reactions of the aqueous cations Mg2+, Ca2+ and Ba2+ with OH‒, CO3
2‒ and SO42‒ ions
OH⁻: Mg²⁺ forms a slight white precipitate, while Ca²⁺ and Ba²⁺ form little to no precipitate due to increasing solubility down the group.
CO₃²⁻: All form white precipitates as their carbonates are insoluble in water.
SO₄²⁻: Mg²⁺ and Ca²⁺ form slight white precipitates, but Ba²⁺ forms a dense white precipitate as BaSO₄ is highly insoluble
(g)
colour observed in the flame test for lithium ions
Red flame
(g)
colour observed in the flame test for sodium ions
Orange yellow flame
(g)
colour observed in the flame test for potassium ions
Lilac flame
(g)
colour observed in the flame test for calcium ions
Brick red flame
(g)
colour observed in the flame test for stronium ions
Crimson red flame
(g)
colour observed in the flame test for barium ions
Apple green flame
(h)
trend in general reactivity of Group 1 and Group 2 metals
Reactivity increases down both groups because ionisation energy decreases, making it easier for atoms to lose electrons and form positive ions. Group 1 metals are more reactive than Group 2 as they lose only one electron instead of two.
(i)
trend in thermal stability of the Group 2 carbonates and hydroxides
Thermal stability increases in both as you go down the group.
(j)
trends in solubility of Group 2 hydroxides and sulfates
The solubility of Group 2 hydroxides increases down the group.
The solubility of Group 2 sulfates decreases down the group
(k)
What is produced when a Group 1 or Group 2 hydroxide reacts with a dilute acid?
Salt and water
(k)
What is produced when a Group 1 or Group 2 oxide reacts with a dilute acid?
Salt and water
(l)
trend in volatility of Group 7 elements (halogens)
The volatility of Group 7 (halogens) decreases down the group. This is because the strength of London dispersion forces increases as the number of electrons and molecular size increase, requiring more energy to overcome intermolecular forces.
(m)
reactions of the halogens with metals
A salt is produced.
(n)
trend in reactivity of the halogens in terms of relative oxidising power
Reactivity decreases down Group 7. This means the oxidising power of the halogens also decreases down the group because it is harder for the atom to gain an electron.
(o)
reaction between aqueous Ag+
and halide ions followed by dilute aqueous NH3
To test for halide ions, add nitric acid followed by silver nitrate solution, then dilute ammonia:
Cl⁻ (Chloride): White precipitate, dissolves in dilute NH₃
Br⁻ (Bromide): Cream precipitate, dissolves slightly in dilute NH₃
I⁻ (Iodide): Pale yellow precipitate, insoluble in dilute NH₃
(p)
Redox reaction
A redox reaction is one in which oxidation and reduction occur on different species simultaneously.
(p)
When does a halogen displacement reaction occur?
When a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide.
(q)
common use of chlorine and fluoride ions
Chlorine is added to drinking water to kill bacteria and prevent diseases like cholera and typhoid. It is safe in low concentrations (below 1 ppm).
Fluoride is added to reduce tooth decay and strengthen bones, helping prevent osteoporosis. It is also safe below 1 ppm.
(q)
health and ethical issues of use of chlorine and fluoride ions in water treatment
Some argue chlorine is toxic and should not be added to water. Others believe people should have a choice about water treatment rather than it being enforced.
(r)
precipitation reaction
A reaction in which two soluble salts combine to form an insoluble salt. The precipitate is filtered, washed, and dried.
(r)
soluble salt formation
Soluble salts are typically formed by neutralising an acid. Any excess solid is filtered, and the solution is evaporated to form crystals.
