Question

1. which element is a metalloid? a) carbon b) silicon c) calcium d) neon 4. which is an example of a diatomic molecule? a) nacl b) o₂ c) co₂ d) he 5. the number of protons in an atom equals the atomic number. 6. the vertical columns in the periodic table are called groups. 7. a neutral atom of oxygen has 8 protons and 8 electrons. 8. chlorine and bromine belong to the halogen family. match the family with the correct description: a. alkali metals b. halogens c. noble gases d. alkaline earth metals 9. very stable, do not react easily: 10. found in group 1, very reactive: 11. found in group 17, form salts with metals: 12. found in group 2, fairly reactive:

Explanation:

Step1: Recall element - type definitions

Metalloids have properties intermediate between metals and non - metals. Carbon is a non - metal, silicon is a metalloid, calcium is a metal, and neon is a noble gas. So for question 4, the answer is B. Silicon.

Step2: Recall diatomic molecule concept

Diatomic molecules consist of two atoms. NaCl is a compound, O₂ is a diatomic molecule, CO₂ is a compound, and He is a monatomic noble gas. So for question 5, the answer is B. O₂.

Step3: Recall periodic table structure

The vertical columns in the periodic table are called groups or families. The number of protons in an atom is the atomic number. A neutral atom has equal numbers of protons and electrons. So for question 6, the answer is groups.

Step4: Recall oxygen's electron configuration

A neutral atom of oxygen has 8 protons and 8 electrons.

Step5: Recall halogen properties

Chlorine and bromine belong to the halogen family. Halogens are very reactive non - metals.

Step6: Recall alkali metal properties

Alkali metals (Group 1 elements) are very reactive.

Step7: Recall noble gas properties

Noble gases (Group 18 elements) are very stable and do not react easily.

Step8: Recall alkaline earth metal location

Alkaline earth metals are found in Group 2 and are fairly reactive.

Step9: Recall halogen - metal reaction

Halogens (Group 17 elements) form salts with metals.

Answer:

1. B. Silicon
2. B. O₂
3. groups
4. 8
5. B. Halogens
6. C. Noble gases
7. A. Alkali metals
8. B. Halogens
9. D. Alkaline earth