Question

independent work

1. which of these determines the identity of an element?

a) number of electrons
b) number of protons
c) number of energy levels
d) number of neutrons

1. fill out the table below:

element	protons	neutrons	electrons	atomic mass
gold			79	197
nitrogen				14
calcium	20	20

1. sodium is an element found in table salt. it contains 11 protons and 12 neutrons. how many electrons are found in a neutral atom of sodium?

a) 23
b) 12
c) 11
d) 1

1. elements are described as pure substances because

a) they are all found in nature
b) they cannot be separated into parts by physical means
c) they have no charge
d) they can be produced in a laboratory

extra exploration section below!

1. the nucleus of an atom contains

a) only neutrons
b) protons and electrons
c) protons and neutrons
d) only electrons

1. draw a diagram of an atom to you. in your diagram, be sure to include the following parts:

• protons, neutrons, electrons and the nucleus

center circle -> label nucleus

• ( p^+ ) (protons)
• ( n^0 ) (neutrons)

Explanation:

Question 1

The identity of an element is determined by the number of protons (atomic number). Electrons can change in ions, energy levels vary, and neutrons change isotopes, but protons define the element.

Step1: Recall neutral atom electron-proton relation

In a neutral atom, number of electrons = number of protons.

Step2: Apply to sodium

Sodium has 11 protons, so electrons = 11.

Pure substances (elements/compounds) can’t be separated into simpler substances by physical means. Elements are pure as they have only one type of atom, and physical methods can’t split them. Other options are incorrect (e.g., not all elements are natural, charge isn’t related, production in lab doesn’t define purity).

Answer:

b. Number of protons

Question 2

To fill the table, we use:

• Electrons in neutral atom = Protons.
• Atomic Mass = Protons + Neutrons.

Titanium:

Neutrons = Atomic Mass - Protons = \( 48 - 22 = 26 \).
Electrons = Protons = \( 22 \).

Gold:

Protons = Electrons (neutral) = \( 79 \).
Neutrons = Atomic Mass - Protons = \( 197 - 79 = 118 \).

Nitrogen:

Protons (atomic number of N) = \( 7 \).
Neutrons = Atomic Mass - Protons = \( 14 - 7 = 7 \).
Electrons = Protons = \( 7 \).

Calcium:

Electrons = Protons = \( 20 \).
Atomic Mass = Protons + Neutrons = \( 20 + 20 = 40 \).

Element	Protons	Neutrons	Electrons	Atomic Mass
Gold	79	118	79	197
Nitrogen	7	7	7	14
Calcium	20	20	20	40

Question 3