# 2.7: Unit 2 Practice Problems

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### Question 1.

Which subatomic particle(s) determine an atom's name?

protons and neutrons

Which subatomic particle(s) determine an atom's mass?

protons and neutrons

Which subatomic particle(s) determine an atom's charge?

electrons and protons

### Question 2.

Write the symbol for each of the following ions:

(a) the ion with a 1+ charge, atomic number 55, and mass number 133

(b) the ion with 54 electrons, 53 protons, and 74 neutrons

(c) the ion with atomic number 15, mass number 31, and a 3− charge

(a) 133Cs+1   (b) 127I-1  (c) 31P-3

### Question 3.

How many protons, neutrons, and electrons are in the following?

(a)   87Sr+2

(b)   75As

(a) protons = 38     neutrons = 49    electrons = 36
(b) protons = 33    neutrons = 42   electrons = 33

### Question 4.

According to Bhor's model, how many electrons are in the 4th energy level?

# electrons = 2(4)2 = 32 electrons

### Question 5.

Give the electron configuration for Ge using quantum mechanical notation.

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2

### Question 6.

Give the electron configuration for Lu using noble gas configuration.

[Xe] 6s2 4f14 5d1

### Question 7.

Give the electron configuration for S-2 using quantum mechanical notation.

1s2 2s2 2p6 3s2 3p6

### Question 8.

Which atom has the electron configuration: 1s22s22p63s23p64s23d104p65s24d2?

Zr