Question

1. what does the tool called symbol tell you about what parts are in an atom or ion?

● what rules can you use to tell how many protons, neutrons and electrons make up an atom or ion?
● check your ideas and write down two examples that show your rules work and include a drawing for each.
● tell what each number on the symbol means and how you find it.

Explanation:

Step1: Understand atomic symbol components

The general form of an atomic symbol is $_{Z}^{A}X^{n\pm}$, where $X$ is the chemical - symbol of the element, $Z$ is the atomic number, $A$ is the mass number, and $n$ is the charge. For the given $_{2}^{3}He^{ + 1}$:

• The sub - script number (2) is the atomic number ($Z$). It tells the number of protons in the nucleus of an atom or ion. So, for $He$, the number of protons $p = 2$.
• The mass number ($A$) is the sum of protons and neutrons in the nucleus. Here, $A = 3$. So the number of neutrons $n=A - Z=3 - 2 = 1$.
• The charge ($+ 1$) indicates that the ion has lost 1 electron. For a neutral atom, the number of electrons $e$ is equal to the number of protons. For this $He^{+1}$ ion, the number of electrons $e=p - 1=2 - 1 = 1$.

Step2: Provide examples

Example 1: $_{11}^{23}Na$ (sodium atom)

• Protons: The atomic number $Z = 11$, so the number of protons $p = 11$.
• Neutrons: Mass number $A = 23$, so the number of neutrons $n=A - Z=23 - 11 = 12$.
• Electrons: Since it is a neutral atom, the number of electrons $e=p = 11$.

Example 2: $_{16}^{32}S^{2 - }$ (sulfide ion)

• Protons: The atomic number $Z = 16$, so the number of protons $p = 16$.
• Neutrons: Mass number $A = 32$, so the number of neutrons $n=A - Z=32 - 16 = 16$.
• Electrons: The charge is $2 -$, so the number of electrons $e=p + 2=16+2 = 18$.

Answer:

The sub - script number in an atomic symbol is the atomic number which gives the number of protons. The mass number (sup - script) is the sum of protons and neutrons. For a neutral atom, the number of electrons equals the number of protons. For an ion, the number of electrons is adjusted according to the charge. Examples: For $_{11}^{23}Na$, $p = 11$, $n = 12$, $e = 11$; for $_{16}^{32}S^{2 - }$, $p = 16$, $n = 16$, $e = 18$.