Question

give the number of valance and core electrons for each. valence electrons are from the group number. core electrons are not valence electrons. it is valence electrons that are gained or lost in a chemical reaction. na has 1 valence electrons and 2 core electrons. na+1 has 3 valence electrons and 4 core electrons. k has 5 valence electrons and 6 core electrons. k+1 has 7 valence electrons and 8 core electrons. a. 0 b. 1 c. 2 d. 3 e. 4 f. 5 g. 6 h. 7 i. 8 j. 9 k. 10 l. 11 m. 12 n. 13 o. 14 p. 15 q. 16 r. 17 s. 18 t. 19 u. 20

Explanation:

Step1: Determine electrons for Na

Sodium (Na) has atomic number 11. It is in Group 1 of the periodic table, so it has 1 valence electron. Core electrons = Total electrons - Valence electrons = 11 - 1=10.

Step2: Determine electrons for Na⁺

When Na loses 1 electron to form Na⁺, it has 10 electrons in total. Since it has a noble - gas electron configuration (like neon), the number of valence electrons is 8 and core electrons is 2 (the inner - most shell electrons).

Step3: Determine electrons for K

Potassium (K) has atomic number 19. It is in Group 1 of the periodic table, so it has 1 valence electron. Core electrons = Total electrons - Valence electrons = 19 - 1 = 18.

Step4: Determine electrons for K⁺

When K loses 1 electron to form K⁺, it has 18 electrons in total. Since it has a noble - gas electron configuration (like argon), the number of valence electrons is 8 and core electrons is 10.

Answer:

1. B. 1
2. K. 10
3. I. 8
4. C. 2
5. B. 1
6. S. 18
7. I. 8
8. K. 10