Question

1. how will you use your periodic table to find the number of neutrons?

1. what do an atom, ion and isotope of an element have in common?
2. how are atoms, ions, and isotopes different?

1. complete the following table:

name	symbol	atomic number	mass number	number of neutrons	number of electrons	charge
sodium-22	$^{22}$na$^+$				10.
		12	24		12
		12	25		10
	$^{46}$ti$^{+2}$
	$^{107}$ag
	$^{19}$f$^{-1}$
					6
carbon-12					6
carbon-14
	$^4$he
		8		8	10
		18			18
argon-40
	$^{70}$ga			8
		7		8	10

1. to test your knowledge of isotopes, list all the pairs of atoms in the table above that are isotopes of each other.

Explanation:

Question 3:

To find neutrons, use the periodic table to get the atomic number (protons) and the isotope's mass number. Subtract atomic number from mass number.

Question 4:

All three have the same number of protons, so they belong to the same element (same atomic number).

Question 5:

• Atoms: Neutral, equal protons/electrons.
• Ions: Charged, unequal protons/electrons.
• Isotopes: Same protons, different neutrons/mass numbers.

Question 6:

Use these rules:

1. Atomic number = number of protons (from element identity).
2. Mass number = protons + neutrons.
3. Number of electrons = protons - charge (charge: + for cation, - for anion).
4. Charge = protons - electrons.

Question 7:

Isotopes share the same atomic number (same element) but different mass numbers.

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Answer:

3.

Locate the element's atomic number (protons) on the periodic table, then use the formula:
$\text{Number of neutrons} = \text{Mass number} - \text{Atomic number}$

4.

They all have the same number of protons (same atomic number), meaning they are the same element.

5.

• Atoms are neutral (protons = electrons); ions have a net charge (protons ≠ electrons); isotopes have the same number of protons but different numbers of neutrons (different mass numbers).

6.

Name	Symbol	Atomic number	Mass Number	Number of neutrons	Number of Electrons	Charge
sodium-22	$^{22}\text{Na}^+$	11	22	11	10	+1
magnesium-24	$^{24}\text{Mg}$	12	24	12	12	0
magnesium-25 cation	$^{25}\text{Mg}^{+2}$	12	25	13	10	+2
titanium-46 cation	$^{46}\text{Ti}^{+2}$	22	46	24	20	+2
silver-107	$^{107}\text{Ag}$	47	107	60	47	0
fluorine-19 anion	$^{19}\text{F}^{-1}$	9	19	10	10	-1
carbon-12	$^{12}\text{C}$	6	12	6	6	0
carbon-14	$^{14}\text{C}$	6	14	8	6	0
helium-4	$^4\text{He}$	2	4	2	2	0
oxygen-16 anion	$^{16}\text{O}^{-2}$	8	16	8	10	-2
argon-40	$^{40}\text{Ar}$	18	40	22	18	0
gallium-70	$^{70}\text{Ga}$	31	70	39	31	0
nitrogen-15 anion	$^{15}\text{N}^{-3}$	7	15	8	10	-3

7.

1. carbon-12 ($^{12}\text{C}$) and carbon-14 ($^{14}\text{C}$)
2. magnesium-24 ($^{24}\text{Mg}$) and magnesium-25 cation ($^{25}\text{Mg}^{+2}$)