Periodic table Flashcards
(29 cards)
What is meant by periodicity?
The repeating patterns in the periodic table
Give an chemical explanation for the following statement. Potassium is placed immediately after argon in the periodic table
Potassium atoms have one more proton than argon
Define the term first ionisation energy
The energy required to remove an electron from each atom in one mole of atoms in the gaseous state
Why do successive ionisation energies increase with ionisation number?
Radius decreases and attraction between electrons and nucleus increases
Explain how successive ionisation energies provide evidence for the electron shells in an atom
Large difference shows a new shell
Explain which block in the periodic table sodium and magnesium belong to
S-block and outer electron is in a s-orbital
Why are silicon, carbon dioxide, oxygen and chlorine all classified as p-block elements?
Outer electron in a p-orbital
Explain the difference in melting point for the elements Na and Mg
- Magnesium ions have a greater charge
- Magnesium has more electrons
- Magnesium has stronger metallic bonds
Explain the trend across period 2
- Number of protons increases
- Outermost electrons experience the same shielding
- Greater nuclear attraction on outermost electrons
- Ionisation energy increases
Describe and explain the trend, down the group, in the reactivity of the Group 2 elements with water
- Reactivity increases down the group
- Atomic radius increases
- There is more shielding
- The nuclear attraction decreases
- Ionisation energy decreases
What is the common use for NaClO?
Bleach
What is the equation for bleach?
2NaOH + Cl2 -> NaCl + NaClO + H2O
Write equations for these two reactions of chlorine with sodium hydroxide
1) Equation for reaction with dilute sodium hydroxide
2) Equation for reaction with hot concentrated sodium hydroxide
1) Cl2 + 2NaOH -> NaClO + NaCl + H2O
2) 3Cl2 + 6NaOH -> NaClO3 + 5NaCl + 3H2O
What conditions are needed to make bleach?
Cold and dilute sodium hydroxide
What is a positive and negative of chlorine?
- Positive = kills bacteria
- Negative = toxic
Write an equation to show how HClO can form in drinking water
Cl2 + H2O -> HClO + HCl
Using aqueous silver nitrate, it is sometimes difficult to distinguish between chloride, bromide and iodide ions. How can aqueous ammonia be used to distinguish between these three ions?
- AgCl dissolves in NH3(aq)
- AgBr dissolves in conc NH3(aq)/partially soluble in NH3(aq)
- AgI insoluble in NH3(aq)
What colour are the precipitates formed from the chloride, bromide and iodide ions?
- Chloride ions = white precipitate
- Bromide ions = cream precipitate
- Iodide ions = yellow precipitate
What is the ionic equation for the formation of a precipitate?
Ag+(aq) + X-(aq) -> AgX(s)
Add Br2 to NaCl
Cyclohexane layer turns orange
Add Br2 to NaI
- Cyclohexane layer turns purple
- Br2 + 2I- -> I2 + 2Br-
Add Cl2 to NaBr
- Cyclohexane layer turns orange
- Cl2 + 2Br- -> Br2 + 2Cl-
Why should displacement reactions involving bromine be carried out in well ventilated areas?
Bromine is toxic
State and explain the trend in the boiling points of chlorine, bromine and iodine
- Boiling points increase down the group
- Greater number of electrons/stronger London forces
- More energy needed to break London forces
