Question

lecture - practice
ent below, identify the amount of ea
3
li
lithium
6.94
protons: 3
neutrons:
electrons:

Explanation:

Step1: Recall atomic number concept

The atomic number of an element is equal to the number of protons. For lithium (Li), the atomic number is 3, so the number of protons is 3.

Step2: Recall mass - number formula

The mass number of an element is approximately the sum of protons and neutrons. The mass number of lithium is approximately 7 (from the 6.94 on the periodic - table entry, we can round it to 7 for simplicity). Since the number of protons is 3, the number of neutrons $n$ can be calculated using the formula $A=p + n$, where $A$ is the mass number and $p$ is the number of protons. So $n=A - p=7 - 3 = 4$.

Step3: Recall charge - neutrality principle

In a neutral atom, the number of electrons is equal to the number of protons. Since lithium is a neutral atom and has 3 protons, it has 3 electrons.

Answer:

Neutrons: 4
Electrons: 3