Question

1. a teacher designs a demonstration to show the similarity of the physical and chemical properties of alkali metals using the procedure below.

prepare the pieces of metal and store them under oil. using the metal tweezers, remove a large piece of the alkali metal from the oil and place on a damp paper towel. place the metal on a tile and, using a scalpel or sharp knife, cut pieces of lithium (5 mm cubes), sodium (4 mm cubes) and potassium (3 mm cubes). create an electrical circuit with each metal to demonstrate that alkali metals are good conductors of electricity.
which of the following is problematic about the teachers procedure?
(a) the teacher uses metal tweezers to handle the alkali metals, which will damage the low - density alkali metals.
(b) the teacher uses a damp paper towel, which will cause a reaction to occur between the alkali metals and the water held in the paper towel.
(c) the teacher uses differently sized samples of alkali metals, which will skew the results of the conductivity demonstration.
(d) the teacher uses a circuit to demonstrate conductivity, which will cause the temperature of the alkali metals to rise above their melting point.

1. which particle has the same electron configuration as a stable potassium ion?

(a) fluoride ion
(b) sodium ion
(c) neon atom
(d) argon atom
use these answers for questions 25 - 28. note that some answers may be used once, more than once, or not at all:
(a) (1s^{2}2s^{2}2p^{6}3s^{2}3p^{5})
(b) (1s^{2}2s^{2}2p^{6}3s^{2}3p^{6})
(c) (1s^{2}2s^{2}2p^{6}2d^{10}3s^{2}3p^{6})
(d) (1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{3})

1. an impossible electronic configuration
2. the ground - state configuration for the atoms of a transition element
3. the ground - state configuration of a negative ion of a halogen
4. the ground - state configuration of a common ion of an alkaline earth element

Explanation:

23.

Alkali metals react vigorously with water. A damp paper towel contains water. When alkali metals (like lithium, sodium, potassium) come in contact with water, they react. For example, \(2Na + 2H_2O=2NaOH + H_2\uparrow\). Using a damp paper towel is problematic as it will cause a reaction between the alkali metals and water.

• Option (A): Metal tweezers are a proper tool to handle alkali metals (they are not damaged by tweezers).
• Option (C): Different - sized samples (if they are in the solid state and just for conductivity demonstration) do not skew the results of showing that alkali metals are good conductors.
• Option (D): Demonstrating conductivity with a circuit does not raise the temperature of alkali metals above their melting point (the electrical current in a simple conductivity - demonstration circuit is not sufficient for that).

A stable potassium ion (\(K^{+}\)) has an electron configuration of \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}\).

• Fluoride ion (\(F^{-}\)) has an electron configuration of \(1s^{2}2s^{2}2p^{6}\).
• Sodium ion (\(Na^{+}\)) has an electron configuration of \(1s^{2}2s^{2}2p^{6}\).
• Neon atom (\(Ne\)) has an electron configuration of \(1s^{2}2s^{2}2p^{6}\).
• Argon atom (\(Ar\)) has an electron configuration of \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}\), which is the same as a stable \(K^{+}\) ion.

In electron configuration, the \(3d\) orbitals fill after the \(4s\) orbital. The order of filling is based on the Aufbau principle (\(n + l\) rule). For option (D) \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{3}\), the \(4s\) orbital should fill before the \(3d\) orbital, but writing \(3d\) before \(4s\) (in the way of \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{3}4s^{2}\) is the correct order when writing the full configuration, and \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{3}\) is an incorrect representation of the filling order). Options (A) \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{5}\) (e.g., for \(Cl\) atom), (B) \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}\) (e.g., for \(Ar\) atom or \(K^{+}\) ion), and (C) \(1s^{2}2s^{2}2p^{6}3d^{10}3s^{2}3p^{6}\) (for \(Zn^{2 +}\) ion) follow the Aufbau principle.

Answer:

B

24.