Question 1

Which of the following best describes a compound?

Accepted Answer

A homogeneous, pure substance made up of two or more different kinds of atoms.

Question 2

Which element is NOT found 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

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 5

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

Accepted Answer

43 protons, 56 neutrons, 43 electrons

Question 6

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

Accepted Answer

Atomic number, number of protons, number of electrons

Question 7

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

Accepted Answer

Two ($$s^2)$$

Question 8

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

Accepted Answer

Mg

Question 9

Which element has the greatest ionization energy?

Accepted Answer

F

Question 10

How many electrons does sulfur (S) need to fill its octet?

Accepted Answer

2

Question 11

What is the Lewis symbol for sulfur (S)?

Accepted Answer

S with 6 dots

Question 12

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

Accepted Answer

2

Question 13

What ion do you expect potassium (K) to form?

Accepted Answer

$$1+$$ ($$\mathrm{K^+})$$

Question 14

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

Accepted Answer

$$\mathrm{CaO}$$

Question 15

Which of the following is a polyatomic ion commonly found in biological systems?

Accepted Answer

$$\mathrm{NH_4$^+} ($$ammonium)

Question 16

Which property increases as you move from left to right across a period in the periodic table?

Accepted Answer

Ionization energy

Question 17

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

Accepted Answer

They have a full valence shell of electrons.

Question 18

A neutral atom of oxygen has how many electrons?

Accepted Answer

8

Question 19

Which of the following is true about cations?

Accepted Answer

They have more protons than electrons.

Building Blocks of Molecules: Matter, Atoms, Elements, and the Periodic Table

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