$$43$$\text{ protons},\ 56\text{ neutrons},\ 43\text{ electrons}$

Question 1

Which of the following best describes a compound?

Accepted Answer

A homogeneous, pure substance composed of two or more different kinds of atoms chemically bonded together.

Question 2

Which element is NOT present in significant amounts in the human body?

Accepted Answer

Fluorine (F)

Question 3

How many nitrogen (N) atoms are present in 2 molecules of caffeine ($$\mathrm{C_8H_{10}N_4O_2}$$)?

Accepted Answer

$$8$$

Question 4

A neutral atom of technetium-99 ($$^{99}_{43}\mathrm{Tc}) $$has how many protons, neutrons, and electrons?

Accepted Answer

$$43$$	ext{ protons},\ 56	ext{ neutrons},\ 43	ext{ electrons}$

Question 5

Which of the following numbers are identical for the neutral isotopes carbon-12 and carbon-14?

Accepted Answer

Atomic number, number of protons, number of electrons

Question 6

What is the molecular weight of glucose ($$\mathrm{C_6H_{12}O_6$}$$)? (Use: $$\mathrm{C}=12.01$$, $$\mathrm{H}=1.01$$, $$\mathrm{O}=16.00)$$

Accepted Answer

$$180\ \mathrm{u}$$

Question 7

Which of the following elements is the largest in atomic size?

Accepted Answer

Mg

Question 8

Which element has the greatest ionization energy?

Accepted Answer

F

Question 9

How many valence electrons do calcium (Ca) and strontium (Sr) both have?

Accepted Answer

two ($$s^2)$$

Question 10

According to the octet rule, how many more electrons does sulfur (S) need to fill its valence shell?

Accepted Answer

2

Question 11

How many covalent bonds does sulfur (S) typically form to fill its octet?

Accepted Answer

2

Question 12

Which of the following ions is most likely formed by potassium (K)?

Accepted Answer

$$1+ (K$^+)$$

Question 13

Which of the following is a common biological polyatomic ion?

Accepted Answer

NH$$_4^+ ($$ammonium ion)

Question 14

What is the correct formula for the binary ionic compound formed between calcium (Ca) and oxygen (O)?

Accepted Answer

CaO

Question 15

Which of the following best explains why noble gases are generally unreactive?

Accepted Answer

They have a full valence shell of 8 electrons.

Question 16

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons.

Question 17

A patient receives a radiology scan using technetium-99. What property of this isotope makes it useful for medical imaging?

Accepted Answer

It emits detectable radiation without significantly altering chemical properties.

Question 18

Which of the following best describes the trend in atomic size across a period (left to right) in the periodic table?

Accepted Answer

Atomic size decreases due to increased nuclear charge pulling electrons closer.

Question 19

Which of the following best describes a cation?

Accepted Answer

An ion with more protons than electrons, positively charged.

Question 20

Which of the following is the correct Lewis symbol for sulfur (S)?

Accepted Answer

S with 6 dots

Building Blocks of Molecules: Matter, Atoms, Elements, and Compounds

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