Assessment for inorganic chemistry 1

Assessment for inorganic chemistry 1

Unit 2: Assessment for inorganic chemistry 1

Periodicity

Question 1

1. Nitrogen-(2,5)
2. Potassium-(2,8,8,1)
3. Arsenic -(2,8,18,5)
4. Vanadium-(2,8,8,5)

Question 2(a)

• Across the period, from left to right, there is an increase in the number of valence electrons.
• Melting point and boiling point increase across period three except for the silicon case
• There is a decrease in atomic radii across period 3 elements.
• Across the period, elements become less metallic.
• Across the period, there is an increase in ionization energy.
• The ionic radius decreases across period 3

(b)

Silicon possesses a giant covalent structure. Each atom shares each in the outer electrons with another bit (silicon); its existence in giant covalent nature makes it have a high melting point of 1414 degrees Celsius. Multiple strong covalent bonds have to be broken, requiring more energy. Phosphorous consists of atoms held by a stigma bond requiring energy to break. This leads to a simple covalent structure; breaking weaker London forces is not as hard as a covalent bond, making it have a low melting point of 44 degrees Celsius.

(c)

Chlorine

Question 3

• The nuclear charge across the period increases this is because of an increase in the number of protons, yes, the electrons are more, but extra electron entering the nuclear making increase in shielding effects negligible, this increases the force of attraction in the nucleus, decreasing the radius across the period.
• First, ionization energy increases across the period and decreases, it decreases between magnesium and aluminum then increases, and it also decreases from phosphorous to Sulphur then rises again. Between magnesium and aluminum, magnesium has fewer cells close to the nucleus; therefore, the force of attraction between the nucleus and electron decreases meaning more energy is required. In sulfur, the 3 electrons in the last energy level are all paired while phosphorous has two paired and one unpaired; this results in a slight decrease in first ionization energy, with sulfur having the lower. Generally, first ionization energy increases across the period.
• Electronegativity increases across the period because there is an increase in the number of charges in the nucleus, making a pair of bonding attract strongly.

Group 2 elements

Question 1

Strontium undergoes chemical reaction readily. The strontium reaction will produce bubbles of hydrogen gas and a colorless solution faster than calcium because the response becomes more vigorous down the group.

Question 2

• Y
• Y
• Each element down group two has an extra shell electron; the outermost shell is far from the nucleus, weakening attraction between positive and negative electrons leading to a decrease in ionization energy. In the melting point, the larger the atomic radii, the larger the bonding distance between electrons reducing the overall reaction and weakening the bond.

Question 3

(a)Group II hydroxides increase in solubility as you down the group

(b)Group II sulfates decreases

(c)hydroxide, there is a decrease in hydroxide salt lattice energy and an increase in the coordination of metals down the group making it more soluble. Sulfates lattice enthalpy decreases down the hydration enthalpy also reduces, but since the hydration enthalpy decreases faster than lattice enthalpy in group II, this minimizes the solubility

Group 7 elements

Question 1

(a)Fluorine

(b)Boiling point increases down the group

(c)Iodine, Bromine

Question 2

(a)There is the formation of a yellow crystalline solid, sodium chlorate. The light heat it. Apart from speeding up the reaction rate, chlorine gas is reduced to ClO^– and also oxidized to Cl^–

(b)The blue litmus paper will turn red, .and red litmus paper will remain red; this is because of the formation of hypochlorite, an unstable compound decomposing to give HCL and oxygen.

(c)The test solution is first acidified using hydrochloric acid

Then you add three drops of barium chloride, then observe if white precipitate is formed. If a deposit is created, then sulfate ions present.

• Acid is drained to the compound to be tested, e.g., hydrochloric acid, observe if bubbles are released, giving a hint of carbon IV oxide. To try the gas, you have to drain it to lime water, turning from clear to milky.

Question 3

(a) Cl₂ + H₂O -> HOCl + H⁺ + OCl

(b)

Chlorine kills an effectively wide variety of microbial pathogens, including cholera, dysentery, and typhoid.

(d)Chlorine in water can lead to bad taste and odor; being a chemical staff, it increases the risk of cancer, cell damage, and increase risk of asthma

(d)

Disproportionation is a redox reaction in which a single reactant is both oxidized and reduced.