Summative Quiz

Who is credited with proposing the first atomic theory?

• Erwin Schrödinger

• John Dalton

• Niels Bohr

• Albert Einstein

Answer explanation

John Dalton is credited with proposing the first atomic theory in the early 19th century, which laid the foundation for modern chemistry by introducing the idea that matter is composed of indivisible atoms.

Which of the following particles is found in the nucleus of an atom?

(Check all that apply)

• Neutrons

• Electrons

• Photons

• Quarks

• Protons

Answer explanation

Neutrons and protons are the particles found in the nucleus of an atom. Electrons orbit the nucleus, while photons are particles of light and quarks are constituents of protons and neutrons.

The charge of an electron is:

• Positive

• Negative

• Neutral

Answer explanation

The charge of an electron is negative, which is a fundamental property of this subatomic particle. This distinguishes it from protons, which have a positive charge, and neutrons, which are neutral.

The mass number of an atom is the total number of:

• Protons and neutrons

• Protons and electrons

• Neutrons and electrons

• Protons, neutrons, and electrons

Answer explanation

The mass number of an atom is defined as the total number of protons and neutrons in its nucleus. Electrons do not contribute to the mass number, as they have negligible mass compared to protons and neutrons.

What is the maximum number of electrons that can occupy the second energy level of an atom?

(NOT THE ORBITALS)

• 4

• 10

• 8

• 2

Answer explanation

The second energy level can hold a maximum of 8 electrons, as determined by the formula 2n², where n is the energy level (n=2). Thus, 2(2)² = 8. Therefore, the correct answer is 8.

The electron configuration for carbon (atomic number 6) is:

• 1s² 2s² 2p⁴

• 1s² 2s² 2p²

• 1s² 2s² 2p¹

• 1s² 2s¹ 2p²

Answer explanation

Carbon has 6 electrons. The correct electron configuration is 1s² 2s² 2p², which accounts for all 6 electrons: 2 in the 1s, 2 in the 2s, and 2 in the 2p subshells.

8. How many lone pairs are there in an oxygen atom?

• 1 lone pair

• 3 lone pairs

• 0 lone pairs

• 2 lone pairs

Answer explanation

An oxygen atom has 6 valence electrons. It forms 2 bonds and has 2 remaining electrons, which are arranged as lone pairs. Therefore, the correct answer is 2 lone pairs.

In the periodic table, elements in the same group have similar:

• Names

• Atomic numbers

• Chemical properties

• Valence Electrons

Answer explanation

Elements in the same group of the periodic table have similar chemical properties due to having the same number of valence electrons, which determine their reactivity and bonding behavior.

What is the periodic trend for electronegativity as you move across a period (left to right)?

• Electronegativity first increases and then decreases across a period.

• Electronegativity increases from left to right across a period.

• Electronegativity remains constant across a period.

• Electronegativity decreases from left to right across a period.

Answer explanation

Electronegativity increases from left to right across a period due to increasing nuclear charge, which attracts bonding electrons more strongly. Thus, the correct answer is that electronegativity increases from left to right.

Which element is located in Group 1 and Period 3?

• Sodium (Na)

• Magnesium (Mg)

• Calcium (Ca)

• Potassium (K)

Answer explanation

Sodium (Na) is the only element listed that is in Group 1 and Period 3 of the periodic table. Magnesium (Mg) is in Group 2, Calcium (Ca) is in Group 2, and Potassium (K) is in Group 1 but in Period 4.