Organic and Inorganic Chemistry

Question 1

What are the trends of atomic and ionic radii across a period?

Answer 1

Atomic radius decreases across a period, while the ionic radius decreases for cations but increases for anions.

Question 2

Define the first ionization energy.

Answer 2

The energy required to remove one electron from a neutral atom in its gaseous state to form a positively charged ion (cation).

Question 3

How does electronegativity change across a period and down a group?

Answer 3

Electronegativity increases across a period due to greater nuclear charge and decreases down a group due to increasing atomic size and shielding effect.

Question 4

What are the chemical properties of Group 2 elements?

Answer 4

They become more reactive down the group, have higher electrode potential, and act as stronger reducing agents as you move down the group.

Question 5

What are the reactions of Group 2 elements with water?

Answer 5

Group 2 metals react with steam to form oxides and hydrogen, and with warm or cold water to form hydroxides and hydrogen gas (except for beryllium and magnesium in cold water).

Question 6

What physical properties do Group 17 elements (halogens) have?

Answer 6

Halogens are diatomic molecules, less thermally stable down the group, and have increasing boiling and melting points down the group.

Question 7

What happens during a halogen displacement reaction?

Answer 7

A more reactive halogen displaces a less reactive halogen from its compound, such as Cl₂ displacing Br₂ from KBr solution.

Question 8

Why does fluorine act as the strongest oxidizing agent among Group 17 elements?

Answer 8

Fluorine has the smallest atomic radius and highest electronegativity, which allows it to attract and gain electrons easily.

Question 9

What is the trend in thermal stability of Group 17 hydrogen halides (e.g., HF, HCl)?

Answer 9

Thermal stability decreases down the group (H-F > H-Cl > H-Br > H-I) due to decreasing bond energy.

Question 10

What is the result of reacting halogens with water?

Answer 10

Fluorine reacts with water to produce HF and oxygen, while chlorine produces HCl and HOCl. Bromine and iodine react similarly but less vigorously.

Question 11

What are the products when a halide reacts with silver nitrate?

Answer 11

Chloride forms a white precipitate (AgCl), bromide forms a cream precipitate (AgBr), and iodide forms a pale yellow precipitate (AgI).

Question 12

What happens to the silver halide precipitates in ammonia?

Answer 12

AgCl dissolves in dilute ammonia, AgBr dissolves in concentrated ammonia, and AgI does not dissolve in ammonia.

Question 13

How does the structure of Period 3 elements change across the period?

Answer 13

It changes from metallic (Na, Mg, Al) to giant covalent (Si) to simple molecular structures (P, S, Cl, Ar).

Question 14

What is the trend in melting and boiling points of Period 3 elements?

Answer 14

Melting and boiling points increase from Na to Si due to stronger metallic and covalent bonds, then decrease from P to Ar due to weak van der Waals forces.

Question 15

What are the acid-base properties of Period 3 oxides?

Answer 15

Na₂O and MgO are basic, Al₂O₃ is amphoteric, and SiO₂, P₄O₁₀, and SO₃ are acidic.

Question 16

How does AlCl₃ change when heated?

Answer 16

AlCl₃ exists as a giant ionic lattice at room temperature, but when heated, it forms Al₂Cl₆ and eventually breaks down into AlCl₃ molecules.

Question 17

What happens when Period 3 chlorides react with water?

Answer 17

NaCl dissolves in water with no change in pH, while MgCl₂ and AlCl₃ hydrolyze to form slightly acidic solutions.

Question 18

Define the shielding effect.

Answer 18

The reduction of the effective nuclear charge on the electron cloud, due to the repulsion between inner electrons and outer electrons.

Question 19

Why do Group 2 carbonates become more thermally stable down the group?

Answer 19

Due to a decrease in charge density as the ion size increases, leading to less polarization of the carbonate ion.

Question 20

What is a displacement reaction?

Answer 20

A reaction where a more reactive element displaces a less reactive element from a compound, often seen with halogens.

Question 21

What is the general trend in ionization energy across the periodic table?

Answer 21

Ionization energy increases across a period and decreases down a group due to atomic size and shielding effects.

Question 22

Why do transition metals exhibit variable oxidation states?

Answer 22

Transition metals have partially filled d-orbitals, allowing them to lose different numbers of electrons and form ions with various charges.

Question 23

What is the difference between an ionic and covalent bond?

Answer 23

An ionic bond involves the transfer of electrons from a metal to a non-metal, while a covalent bond involves the sharing of electrons between two non-metals.

Question 24

Why do noble gases have high ionization energies?

Answer 24

Noble gases have a full valence shell, making them very stable and requiring a lot of energy to remove an electron.