Question

question 1 (2 points)
(03.01 lc)
lithium is located in the first group of the periodic table. how many valence electrons does the element lithium have?
o a 1
o b 2
o c 4
o d 8
question 2 (2 points)
(03.01 mc)
the table shows the total number of electrons in atom a and atom b.
which statement is correct?
o a a will give up electrons to form bonds.
o b b will give up electrons to form bonds.
o c both a and b will be chemically unreactive.
o d both a and b will gain electrons to become stable.
question 3 (2 points)
(03.03 lc)
what is the charge on an atom after it gains two electrons during the formation of a bond?
o a one positive charge
o b two positive charges
o c two negative charges
o d one negative charge

Explanation:

Question 1

Step1: Valence electrons and group number

In the periodic table, for main - group elements (groups 1 - 2 and 13 - 18), the group number (for groups 1 - 2, it directly gives the number of valence electrons; for groups 13 - 18, the group number minus 10 gives the number of valence electrons). Lithium is in group 1.

Step2: Determine the number of valence electrons

Since it is in group 1, the number of valence electrons is 1.

Question 2

Step1: Electron configuration of Atom A

Atom A has 11 electrons. The electron configuration is \(1s^{2}2s^{2}2p^{6}3s^{1}\). The outermost shell (valence shell) has 1 electron. Atoms with 1, 2, or 3 valence electrons tend to give up electrons to form bonds.

Step2: Electron configuration of Atom B

Atom B has 17 electrons. The electron configuration is \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{5}\). The outermost shell (valence shell) has 7 electrons. Atoms with 5, 6, or 7 valence electrons tend to gain electrons to form bonds.

Step3: Analyze each option

• Option a: Atom A has 1 valence electron (from its electron configuration \(1s^{2}2s^{2}2p^{6}3s^{1}\)), so it will give up electrons to form bonds.
• Option b: Atom B has 7 valence electrons (\(1s^{2}2s^{2}2p^{6}3s^{2}3p^{5}\)) and will gain electrons, not give up.
• Option c: Both A and B are reactive. Atom A can lose an electron, and atom B can gain an electron.
• Option d: Atom A will lose, not gain electrons.

Question 3

Step1: Charge of an electron

An electron has a charge of \(- 1\).

Step2: Calculate the charge after gaining two electrons

If an atom gains two electrons, and each electron has a charge of \(-1\), then the total charge is \(2\times(-1)=- 2\) (two negative charges).

Answer:

• Question 1: a. 1
• Question 2: a. A will give up electrons to form bonds
• Question 3: c. Two negative charges