Question

If xenon has an atomic number of 54 and a mass number of 108, how many neutrons does it have?

a. 54
b. 27
c. 100
d. 108

5. Atoms that vary in the number of neutrons found in their nuclei are called ________.
a. ions
b. neutrons
c. neutral atoms
d. isotopes

Potassium has an atomic number of 19.

What is its electron configuration?
a. shells 1 and 2 are full, and shell 3 has nine electrons
b. shells 1, 2 and 3 are full and shell 4 has three electrons
c. shells 1, 2 and 3 are full and shell 4 has one electron
d. shells 1, 2 and 3 are full and no other electrons are present

Which type of bond represents a weak chemical bond?
a. hydrogen bond
b. atomic bond
c. covalent bond
d. nonpolar covalent bond

Answer 1

1. The atomic number is equal to the number of protons in the nucleus, and the mass number is equal to the number of protons and neutros in the nucleus.

Therefore, to find the number of neutrons we must do mass number - atomic number, which equals 54.

Answer 1: a. 54

2. Atoms of a same element that have a different number of neutrons in the nucleus are called isotopes of an element.

Answer 2: d. Isotopes

3. Potassium has an electron configuration of
`[Ar] 4s^(1)`, meaning that the first 3 shells are full, and that the last shell (4th one) has only 1 electron.

Answer 3: c. Shells 1, 2 and 3 are full and shell 4 has one electron.

4. An atomic bond isn't a specific bond, it's just a term. Polar covalent and non-polar covalent bonds are strong bonds, which leaves us with the hydrogen bonds, which are indeed the weakest bonds out there.

Answer 4: a. Hydrogen bond

Hope it helped,

BiologiaMagister