Question

date 17 - 11 - 25
class period 6th
chemistry fall semester final exam review (25 - 26)
the atom

1. which of the following determines what element the atom is?

a. the # of protons b. the # of electrons c. the # of neutrons

1. use the periodic table to complete the following table:

*assume all atoms are electrically neutral.

element name	atomic number	number of protons	number of electrons
	14
		82
sodium (na)
	12

3.. use the periodic table to fill out the following table for the following isotopes.

isotope name	nuclear notation	number of protons	atomic number	number of neutrons	mass number
	$\ce{^{16}_{7}n}$				16
bromine - 82	$\ce{^{82}_{35}br}$
he - 3			2
	$\ce{^{109}_{47}ag}$				109
uranium - 235			92
	$\ce{^{58}_{27}co}$	27

1. isotopes are elements that have the same number of protons, but a different mass because they have a different number of

Explanation:

Question 1

In chemistry, the atomic number (which equals the number of protons) defines an element. Electrons can change in ions, and neutrons vary in isotopes but don't change the element identity. So the number of protons determines the element.

Step1: Recall Atomic Structure Rules

For a neutral atom: Atomic Number = Number of Protons = Number of Electrons. Atomic Number identifies the element (from periodic table).

Step2: Helium (He)

Atomic Number of He is 2. So Protons = 2, Electrons = 2 (neutral). The original filled values (8 protons, 6 electrons) are incorrect. Correct: Atomic Number = 2, Protons = 2, Electrons = 2.

Step3: Atomic Number = 14

Element with Atomic Number 14 is Silicon (Si). Protons = 14, Electrons = 14 (neutral).

Step4: Protons = 82

Atomic Number = 82 (since Protons = Atomic Number). Element is Lead (Pb). Electrons = 82 (neutral).

Step5: Sodium (Na)

Atomic Number of Na is 11. Protons = 11, Electrons = 11 (neutral).

Step6: Atomic Number = 12

Element with Atomic Number 12 is Magnesium (Mg). Protons = 12, Electrons = 12 (neutral).

Element Name	Atomic Number	Number of Protons	Number of Electrons
Silicon (Si)	14	14	14
Lead (Pb)	82	82	82
Sodium (Na)	11	11	11
Magnesium (Mg)	12	12	12

Question 3 (Isotope Table Completion)

Step1: Recall Isotope/Nuclear Notation Rules

• Nuclear Notation: $\ce{^A_Z X}$, where \( A \) = Mass Number, \( Z \) = Atomic Number (Protons), Neutrons = \( A - Z \).
• Isotope Name: Element - Mass Number (Mass Number = Protons + Neutrons).

Step2: Carbon - 14

• Nuclear Notation: $\ce{^{14}_6 C}$ (Z = 6, A = 14).
• Neutrons = \( 14 - 6 = 8 \).
• Mass Number = 14.

Step3: $\ce{^{16}_7 N}$ (Nitrogen - 16)

• Element: Nitrogen (N), Isotope Name: Nitrogen - 16.
• Protons (Z) = 7, Atomic Number = 7.
• Neutrons = \( 16 - 7 = 9 \).

Step4: Bromine - 82, $\ce{^{82}_{35} Br}$

• Protons (Z) = 35, Atomic Number = 35.
• Neutrons = \( 82 - 35 = 47 \).
• Mass Number = 82.

Step5: He - 3

• Nuclear Notation: $\ce{^3_2 He}$ (Z = 2, A = 3).
• Protons = 2.
• Neutrons = \( 3 - 2 = 1 \).
• Mass Number = 3.

Step6: $\ce{^{109}_{47} Ag}$ (Silver - 109)

• Element: Silver (Ag), Isotope Name: Silver - 109.
• Protons (Z) = 47, Atomic Number = 47.
• Neutrons = \( 109 - 47 = 62 \).

Step7: Uranium - 235

• Nuclear Notation: $\ce{^{235}_{92} U}$ (Z = 92, A = 235).
• Protons = 92.
• Neutrons = \( 235 - 92 = 143 \).
• Mass Number = 235.

Step8: $\ce{^{58}_{27} Co}$ (Cobalt - 58)

• Element: Cobalt (Co), Isotope Name: Cobalt - 58.
• Atomic Number (Z) = 27.
• Neutrons = \( 58 - 27 = 31 \).
• Mass Number = 58.

Isotope Name	Nuclear Notation	Number of Protons	Atomic Number	Number of Neutrons	Mass Number
Nitrogen - 16	$\ce{^{16}_7 N}$	7	7	9	16
Bromine - 82	$\ce{^{82}_{35} Br}$	35	35	47	82
He - 3	$\ce{^3_2 He}$	2	2	1	3
Silver - 109	$\ce{^{109}_{47} Ag}$	47	47	62	109
Uranium - 235	$\ce{^{235}_{92} U}$	92	92	143	235
Cobalt - 58	$\ce{^{58}_{27} Co}$	27	27	31	58

Question 4

Answer:

a. The # of Protons

Question 2 (Table Completion)