Question

1. *examine the diagram on the right and calculate...

a. number of electrons =
b. number of protons =
c. number of neutrons =

1. **what is the identity of the element shown on the right?

a. beryllium - 7
b. beryllium - 4
c. lithium - 3
d. lithium - 7
examine the five atoms/ions below. use the information to answer the questions that follow.

a	b	c	d	e

for each of the questions below, circle any and all atoms (a - e) that apply. this means you may have more than one answer circled for each question.

1. **these atoms are isotopes of one another.

a. atom a and atom c
b. atom b and atom c
c. atom b and atom d
d. atom d and atom e

1. **these atom(s) are anion(s).

a. atom a
b. atom b
c. atom c
d. atom d
e. atom e

1. **these atom(s) are cation(s).

a. atom a
b. atom b
c. atom c
d. atom d
e. atom e

1. **these atoms have the same number of neutrons.

a. atom a
b. atom b
c. atom c
d. atom d
e. atom e

1. **these atom(s) have a total of 18 electrons

a. atom a
b. atom b
c. atom c
d. atom d
e. atom e
*what is the mass number of an ion that consists of 20 protons, 20 neutrons, and 18 electrons?
a. 18
b. 20
c. 38
d. 40

Explanation:

Step1: Analyze the first diagram

Count the number of electrons, protons and neutrons from the atomic - structure diagram. There are 4 electrons (represented by the small circles with a negative sign outside the nucleus), 4 protons (represented by the small circles with a positive sign in the nucleus), and 3 neutrons (represented by the small circles without a sign in the nucleus).

Step2: Determine the identity of the element in the first diagram

The atomic number (number of protons) determines the identity of the element. Beryllium has an atomic number of 4. The mass number is the sum of protons and neutrons, which is \(4 + 3=7\). So the element is Beryllium - 7.

Step3: Analyze the isotope concept

Isotopes are atoms of the same element with different numbers of neutrons. Atom A (\(^{32}S^{ - 2}\)) has 16 protons (\(S\) has atomic number 16), 16 electrons (in neutral \(S\)) and \(32-16 = 16\) neutrons. Atom C (\(^{34}S\)) has 16 protons, 16 electrons (neutral atom) and \(34 - 16=18\) neutrons. They are isotopes of sulfur.

Step4: Analyze anions and cations

An anion is a negatively - charged ion. Atom A (\(^{32}S^{ - 2}\)) is an anion as it has a charge of - 2. A cation is a positively - charged ion. Atom D (\(^{36}K^{+1}\)) is a cation as it has a charge of + 1.

Step5: Calculate the number of neutrons for each atom

Atom A: Mass number \(=32\), atomic number \( = 16\), neutrons \(=32 - 16=16\). Atom B: Mass number \(=36\), atomic number \( = 18\), neutrons \(=36 - 18 = 18\). Atom C: Mass number \(=34\), atomic number \( = 16\), neutrons \(=34 - 16=18\). Atom D: Mass number \(=36\), atomic number \( = 19\), neutrons \(=36 - 19 = 17\). Atom E: Mass number \(=39\), atomic number \( = 19\), neutrons \(=39 - 19=20\). Atoms B and C have the same number of neutrons.

Step6: Calculate the number of electrons for each atom

Atom A: Atomic number of \(S\) is 16, and it has a charge of - 2, so electrons \(=16 + 2=18\). Atom B: Atomic number \( = 18\), electrons \(=18\) (neutral atom).

Step7: Calculate the mass number of the ion

The mass number is the sum of protons and neutrons. Given 20 protons and 20 neutrons, the mass number \(=20 + 20=40\).

Answer:

1. a. 4

b. 4
c. 3

1. a. Beryllium - 7
2. a. Atom A and Atom C
3. a. Atom A
4. d. Atom D
5. b. Atom B, c. Atom C
6. a. Atom A, b. Atom B

• d. 40