$$6 \times 12 + 12 \times 1 + 6 \times 16 = 180$$

Question 1

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

Accepted Answer

They have a full valence shell of electrons, making them stable and unlikely to form bonds.

Question 2

A neutral atom of chlorine has an atomic number of 17 and a mass number of 35. How many neutrons does it have?

Accepted Answer

$$35 - 17 = 18$$ neutrons

Question 3

Which of the following best describes a cation?

Accepted Answer

An ion with more protons than electrons, resulting in a positive charge.

Question 4

Which element would you expect to have the highest ionization energy?

Accepted Answer

Neon ($$\mathrm{Ne})$$

Question 5

What is the molecular weight of glucose ($$\mathrm{C_6H_{12}O_6$}$$)? (Atomic weights: C = 12, H = 1, O = 16)

Accepted Answer

$$6 	imes 12 + 12 	imes 1 + 6 	imes 16 = 180$$

Question 6

Which of the following best describes the relationship between atomic number and the identity of an element?

Accepted Answer

The atomic number is the number of protons in the nucleus and uniquely identifies the element.

Question 7

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 8

Which of the following best explains why elements in the same group of the periodic table have similar chemical properties?

Accepted Answer

They have the same number of valence electrons.

Question 9

Which of the following is a correct Lewis dot structure for sodium chloride ($$\mathrm{NaCl}$$)?

Accepted Answer

$$\mathrm{Na^+ :Cl^-}$$

Question 10

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed when two atoms share a pair of electrons.

Question 11

Which of the following elements is most likely to form a cation in an ionic bond?

Accepted Answer

Sodium ($$\mathrm{Na})$$

Question 12

Which of the following best describes the trend in atomic size across a period from left to right?

Accepted Answer

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

Question 13

Which of the following is the correct electron configuration for a neutral atom of carbon ($$\mathrm{C}$$, atomic number 6)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^2$$

Question 14

Which of the following best explains why ionization energy increases across a period?

Accepted Answer

The increasing nuclear charge holds electrons more tightly, requiring more energy to remove an electron.

Question 15

Which of the following is a polyatomic ion?

Accepted Answer

$$\mathrm{SO_4$^{2-}} ($$sulfate)

Question 16

Which of the following statements about valence electrons is correct?

Accepted Answer

Valence electrons are the outermost electrons in the shell of an atom and determine chemical reactivity.

Question 17

Which of the following best describes the difference between a molecule and a compound?

Accepted Answer

A molecule is the smallest unit of a pure substance that retains its properties, while a compound contains atoms of different elements.

Question 18

Which of the following best explains why metals are good conductors of electricity?

Accepted Answer

Metals have loosely held valence electrons that can move freely through the lattice.

Question 19

Which of the following is the correct order of increasing electronegativity for the elements Na, Cl, and F?

Accepted Answer

$$\mathrm{Na \u003c Cl \u003c F}$$

Question 20

A patient is given a medication containing ammonium ion ($$\mathrm{NH_4$^+}). $$Which of the following best describes this ion?

Accepted Answer

A polyatomic cation formed by covalently bonded atoms with an overall positive charge.

Fundamental Concepts in GOB Chemistry: Atoms, Elements, and the Periodic Table

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