Question

1. fill in the blanks: (1 pt each)

symbol atomic # mass # # protons # electrons # neutrons
zn⁺² 30
ir 77 192
p⁻³ 15
64 64

Explanation:

Step1: Recall atomic number and proton - electron relationship

The atomic number is equal to the number of protons. For a neutral atom, the number of electrons is equal to the number of protons. For ions, adjust the number of electrons according to the charge. The mass number is the sum of protons and neutrons.

Step2: Analyze $Zn^{+2}$

The atomic number of $Zn$ is 30, so the number of protons is 30. Since it has a +2 charge, the number of electrons is $30 - 2=28$. The most common isotope of $Zn$ has a mass number of 65, so the number of neutrons is $65 - 30 = 35$.

Step3: Analyze $Ir$

The atomic number is 77, so the number of protons is 77. For a neutral atom, the number of electrons is 77. Given the mass number is 192, the number of neutrons is $192-77 = 115$.

Step4: Analyze $P^{-3}$

The atomic number of $P$ is 15, so the number of protons is 15. Since it has a - 3 charge, the number of electrons is $15+3 = 18$. The most common isotope of $P$ has a mass number of 31, so the number of neutrons is $31 - 15=16$.

Step5: Analyze the unknown element

Since the number of protons is 64 and the number of electrons is 64, the element is neutral. The element with atomic number 64 is Gadolinium ($Gd$). The mass number is not given, but if we assume a common isotope, we can calculate neutrons. Given the number of protons is 64 and electrons is 64, and if we assume a mass - number of 158 (a common isotope of $Gd$), the number of neutrons is $158 - 64=94$.

Answer:

Symbol	Atomic #	Mass #	# protons	# electrons	# neutrons
$Ir$	77	192	77	77	115
$P^{-3}$	15	31	15	18	16
$Gd$	64	158	64	64	94