Question

1.7 1.2.4 interpret simple examples of representing elements and compounds

which isotope is most abundant?
which isotope is least abundant?
what is the identity of element x (which element on the periodic table)?

2b. examine the isotopic symbol for a neutral atom of zinc below. use the information in the model to answer the following questions. remember that atomic number is equal to the number of protons = electrons. mass number is protons + neutrons.

number of protons:
number of electrons:
mass number:
number of neutrons:

2c. interpret the chemical formula below.

$ca_3(po_4)_2$

a. how many calcium atoms are represented?

b. how many phosphorus atoms are represented?

c. how many oxygen atoms are represented?

d. how many phosphate ions, $po_4$ groups, are represented?

2d. below is a particle model representing a chemical reaction. use this particle model to write a chemical equation for the reaction.

chemical equation:

Explanation:

2B.

Step1: Determine protons from atomic number

The atomic number (bottom number) of Zn is 30, so protons = 30.

Step2: Determine electrons in neutral atom

In a neutral atom, electrons = protons, so electrons = 30.

Step3: Determine mass number from symbol

The mass number (top number) is 67.

Step4: Calculate neutrons (mass - protons)

Neutrons = 67 - 30 = 37.

Answer:

• Number of protons: 30
• Number of electrons: 30
• Mass number: 67
• Number of neutrons: 37

2C. For \( \boldsymbol{Ca_3(PO_4)_2} \)

A. Calcium atoms

The subscript for Ca is 3, so 3 calcium atoms.

B. Phosphorus atoms

Inside the parentheses, P has a subscript of 1, and the parentheses have a subscript of 2. So \( 1 \times 2 = 2 \) phosphorus atoms.

C. Oxygen atoms

Inside the parentheses, O has a subscript of 4, and the parentheses have a subscript of 2. So \( 4 \times 2 = 8 \) oxygen atoms.

D. Phosphate ions (\( PO_4 \) groups)

The subscript outside the parentheses is 2, so 2 phosphate ions.