Question

atoms and ions assignment i
symbol # of protons # of electrons electric charge
li+ 3 2 1+
c 6 6 0
f- 9 10 1-
mg2+ 12 10 2+
k+
li 3 3 0
s2- 16 18 - 2
he
18 0
8 2-
17 1-
11 0
ca2+
fe3+
fe2+

Explanation:

Step1: Recall the relationship between protons, electrons and charge

The electric charge of an atom or ion is calculated as the number of protons minus the number of electrons. For a neutral atom, the number of protons equals the number of electrons and the charge is 0. For ions, the charge is non - zero.

Step2: Fill in the table for $K^+$

Potassium ($K$) has an atomic number of 19, so the number of protons in $K^+$ is 19. Since it has a $1+$ charge, the number of electrons is $19 - 1=18$.

Step3: Fill in the table for $He$

Helium ($He$) has an atomic number of 2. For a neutral helium atom, the number of protons is 2, the number of electrons is 2 and the electric charge is 0.

Step4: Fill in the table for the ion with 8 protons and 2 - charge

The element with 8 protons is oxygen ($O$). If it has a $2 -$ charge, the number of electrons is $8+2 = 10$.

Step5: Fill in the table for the ion with 17 protons and 1 - charge

The element with 17 protons is chlorine ($Cl$). If it has a $1 -$ charge, the number of electrons is $17 + 1=18$.

Step6: Fill in the table for the atom with 11 protons

The element with 11 protons is sodium ($Na$). For a neutral sodium atom, the number of electrons is 11 and the charge is 0.

Step7: Fill in the table for $Ca^{2+}$

Calcium ($Ca$) has an atomic number of 20. For $Ca^{2+}$, the number of protons is 20 and the number of electrons is $20 - 2=18$, and the charge is $2+$.

Step8: Fill in the table for $Fe^{3+}$

Iron ($Fe$) has an atomic number of 26. For $Fe^{3+}$, the number of protons is 26 and the number of electrons is $26- 3 = 23$, and the charge is $3+$.

Step9: Fill in the table for $Fe^{2+}$

For $Fe^{2+}$, the number of protons is 26 and the number of electrons is $26 - 2=24$, and the charge is $2+$.

Symbol	# of protons	# of electrons	electric charge
$He$	2	2	0
$O^{2 -}$	8	10	$2 -$
$Cl^-$	17	18	$1 -$
$Na$	11	11	0
$Ca^{2+}$	20	18	$2+$
$Fe^{3+}$	26	23	$3+$
$Fe^{2+}$	26	24	$2+$

Answer:

Symbol	# of protons	# of electrons	electric charge
$He$	2	2	0
$O^{2 -}$	8	10	$2 -$
$Cl^-$	17	18	$1 -$
$Na$	11	11	0
$Ca^{2+}$	20	18	$2+$
$Fe^{3+}$	26	23	$3+$
$Fe^{2+}$	26	24	$2+$