Question

1)

Answer 1

Answer: 1. A) An atom of chlorine has 17 protons.

2. D) The number of protons equals the number of electrons.

Explanation:

1. Atomic number is defined as the number of protons or number of electrons that are present in an atom.

For an electrically neutral atom,

Atomic number = Number of electrons = Number of protons  

As atomic number of chlorine is 17, it has 17 protons and 17 electrons. It can any any number of neutrons depending on the isotope.

2.

Electronic configuration represents the total number of electrons that a neutral element contains. We add all the superscripts to know the number of electrons in an atom.

Mass number is defined as the sum of number of protons and neutrons that are present in an atom.

Number of protons of aluminium = 17

Number of electrons of aluminium = 2=8+7 = 17

Mass number = Number of protons + Number of neutrons  = 17 +18 = 35

Number of protons of aluminium  = Number of electrons of aluminium = 17

Thus atomic number of aluminium is 17 and Number of protons of aluminium  = Number of electrons of aluminium

Answer 2

Answer:

1) B

2) A, B, and D

Explanation:

1) The atomic number provides the number of protons and electrons, since the number of the two are the same.

2) You DO NOT know whether or not the protons are in the nucleus (they are) based on the atomic number, that's just prior knowledge.