Question

Give the symbol of the main-group metals in period 4 with the following number of unpaired electrons per atom. (Transition metals are not included.) (a) 0 (b) 1 (c) 2 (d) 3

Short answer

Question: Identify the symbols of the main-group metals in period 4 with the given number of unpaired electrons per atom: (a) 0 unpaired electrons (b) 1 unpaired electron (c) 2 unpaired electrons (d) 3 unpaired electrons Answer: (a) Ca, Kr (b) K, Ga, Br (c) Ge, Se (d) As

Step-by-step solution

Identify the main-group metals in period 4

Using the periodic table, we can see that the main-group metals in period 4 are elements from groups 1, 2, and 13-18, excluding transition metals. They are: K (Potassium, atomic number: 19), Ca (Calcium, atomic number: 20), Ga (Gallium, atomic number: 31), Ge (Germanium, atomic number: 32), As (Arsenic, atomic number: 33), Se (Selenium, atomic number: 34), Br (Bromine, atomic number: 35), and Kr (Krypton, atomic number: 36).

Determine electron configurations and unpaired electrons

To find the number of unpaired electrons of each element, we need to determine their electron configurations and examine the number of unpaired electrons in the outermost energy level (valence electrons). Here are the electron configurations and unpaired electrons for each element: - K (Potassium, atomic number: 19): [Ar] 4s^1 (1 unpaired electron) - Ca (Calcium, atomic number: 20): [Ar] 4s^2 (0 unpaired electrons) - Ga (Gallium, atomic number: 31): [Ar] 3d^10 4s^2 4p^1 (1 unpaired electron) - Ge (Germanium, atomic number: 32): [Ar] 3d^10 4s^2 4p^2 (2 unpaired electrons) - As (Arsenic, atomic number: 33): [Ar] 3d^10 4s^2 4p^3 (3 unpaired electrons) - Se (Selenium, atomic number: 34): [Ar] 3d^10 4s^2 4p^4 (2 unpaired electrons) - Br (Bromine, atomic number: 35): [Ar] 3d^10 4s^2 4p^5 (1 unpaired electron) - Kr (Krypton, atomic number: 36): [Ar] 3d^10 4s^2 4p^6 (0 unpaired electrons)

Identify the symbols with the given number of unpaired electrons

Now that we have the unpaired electron numbers for each element, we can identify the symbols for each part of the problem: (a) 0 unpaired electrons: Ca (Calcium), Kr (Krypton) (b) 1 unpaired electron: K (Potassium), Ga (Gallium), Br (Bromine) (c) 2 unpaired electrons: Ge (Germanium), Se (Selenium) (d) 3 unpaired electrons: As (Arsenic)