Question

1. what is the group number for each of the following groups; a. noble gasses b. alkaline earth metals c. halogens d. transition metals e. alkali metals 2. name 2 noble gasses. 3. name 3 alkali metals. 4. name 2 transition metals in period 4. 5. what is the term for the rows going across the periodic table? what is similar for all atoms in the same row? 6. what is the term for the columns going down the periodic table? what is similar for all atoms in the same column (except for the transition metals)? 7. how can you use the periodic table to determine the number of valence electrons? 8. how do you calculate the number of core electrons? 9. what are the names of the first and last element in period 3? 10. what are the names of the first and last element in group 2? 11. how can you use the periodic table to determine the number of electron energy levels around a bohr model?

Explanation:

1. a. Noble gases are in group 18. They are known for their stability due to full - valence electron shells.

b. Alkaline earth metals are in group 2. They have 2 valence electrons.
c. Halogens are in group 17. They are highly reactive non - metals.
d. Transition metals are in groups 3 - 12. They have variable oxidation states.
e. Alkali metals are in group 1. They are very reactive metals.

1. Two noble gases are helium and neon.
2. Three alkali metals are lithium, sodium, and potassium.
3. Two transition metals in period 4 are scandium and titanium.
4. The rows going across the periodic table are called periods. All atoms in the same row have the same number of electron shells.
5. The columns going down the periodic table are called groups. All atoms in the same group (except transition metals) have the same number of valence electrons.
6. For main - group elements, the group number (using the 1 - 18 numbering) is equal to the number of valence electrons.
7. The number of core electrons is calculated by subtracting the number of valence electrons from the total number of electrons (equal to the atomic number for a neutral atom).
8. The first element in period 3 is sodium and the last is argon.
9. The first element in group 2 is beryllium and the last is radium.
10. The period number is equal to the number of electron energy levels in the Bohr model.

Answer:

1. a. 18

b. 2
c. 17
d. 3 - 12
e. 1

1. Helium, Neon
2. Lithium, Sodium, Potassium
3. Scandium, Titanium
4. Periods; same number of electron shells
5. Groups; same number of valence electrons
6. For main - group elements, group number = number of valence electrons
7. Total number of electrons - number of valence electrons
8. Sodium, Argon
9. Beryllium, Radium
10. The period number is equal to the number of electron energy levels.