Question 1

Which of the following statements best explains why electrons in higher energy shells are important for chemical reactions?

Accepted Answer

Electrons in higher energy shells have more energy and are farther from the nucleus, making them more likely to be involved in bond formation or loss during chemical reactions.

Question 2

A neutral atom of carbon has an atomic number of 6 and an atomic mass of 12. How many neutrons does it have?

Accepted Answer

$6$ neutrons

Question 3

Which of the following elements is NOT one of the six most abundant elements in the human body?

Accepted Answer

Sodium

Question 4

Which isotope of hydrogen contains one proton, one neutron, and one electron?

Accepted Answer

Deuterium ($^2_1H$)

Question 5

If an atom has 11 protons, 12 neutrons, and 11 electrons, what is its atomic number and mass number?

Accepted Answer

Atomic number $11$, mass number $23$

Question 6

Which of the following best describes the difference between covalent and ionic bonds?

Accepted Answer

Covalent bonds involve the sharing of electron pairs, while ionic bonds involve the complete transfer of electrons from one atom to another.

Question 7

Which of the following electron configurations represents a stable, unreactive atom?

Accepted Answer

An atom with a full valence shell

Question 8

A sodium atom (Na) loses one electron to form a sodium ion (Na$^+$). What is the resulting charge and why?

Accepted Answer

The sodium ion has a $+1$ charge because it has one more proton than electron.

Question 9

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 10

Which of the following best explains why noble gases like neon and argon are chemically unreactive?

Accepted Answer

Their outermost electron shells are completely filled, making them stable and unlikely to form bonds.

Question 11

Which of the following is the correct order of bond strength from strongest to weakest?

Accepted Answer

Covalent bond > Ionic bond > Hydrogen bond > van der Waals interaction

Question 12

Which of the following best describes the role of valence electrons in chemical bonding?

Accepted Answer

Valence electrons are the electrons in the outermost shell and are involved in forming chemical bonds.

Question 13

Which of the following real-world scenarios best illustrates the concept of energy absorption and release by electrons?

Accepted Answer

A fluorescent light emits visible light when electrons fall from higher to lower energy shells, releasing energy as photons.

Question 14

Which of the following is a correct statement about the periodic table?

Accepted Answer

Elements are arranged in order of increasing atomic number, which is the number of protons in the nucleus.

Question 15

A molecule of methane ($CH_4$) is formed when carbon shares electrons with four hydrogen atoms. What type of bond is formed between carbon and hydrogen?

Accepted Answer

Covalent bond

Question 16

Which of the following best explains why water ($H_2O$) is a polar molecule?

Accepted Answer

Oxygen is more electronegative than hydrogen, causing an unequal sharing of electrons and creating partial charges.

Question 17

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak bond between a hydrogen atom covalently bonded to one electronegative atom and another electronegative atom.

Question 18

Which of the following statements about van der Waals interactions is correct?

Accepted Answer

They are weak attractions between molecules due to temporary partial charges.

Question 19

If an atom absorbs energy and an electron moves from the second shell ($n=2$) to the third shell ($n=3$), what happens to the energy of the electron?

Accepted Answer

The electron gains energy as it moves to a higher shell.

Atoms, Elements, and Chemical Bonds: Foundations of General Biology

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