Question

1. how many neutrons are in an atom of lithium? 3 li lithium 6.94 2. how many neutrons are in an atom of hydrogen? 1 h hydrogen 1.01 3. in a neutral atom, this element has an atomic mass of 23 amu and has 11 protons. a. how many neutrons does it have? __________ b. what element is it? ________ 4. in a neutral atom, this element has 5 neutrons and an atomic number of 5. a. what is the atomic mass? ________ b. what element is it? __________

Explanation:

Step1: Recall the formula for number of neutrons

Number of neutrons = Atomic mass - Atomic number

Step2: For lithium

Atomic number of Li is 3 (from the periodic - table symbol), and atomic mass is approximately 7 (rounded from 6.94). So number of neutrons = 7 - 3 = 4

Step3: For hydrogen

Atomic number of H is 1, and atomic mass is approximately 1 (rounded from 1.01). So number of neutrons = 1 - 1 = 0

Step4: For the element with atomic mass 23 AMU and 11 protons

a. Number of neutrons = 23 - 11 = 12
b. The element with atomic number 11 is sodium (Na)

Step5: For the element with 5 neutrons and atomic number 5

a. Atomic mass = Number of protons+Number of neutrons. Since atomic number = number of protons = 5, atomic mass = 5 + 5 = 10
b. The element with atomic number 5 is boron (B)

Answer:

1. 4
2. 0
3. a. 12

b. Sodium (Na)

1. a. 10

b. Boron (B)