Quiz 10/11 Unit 2

Which subatomic particle is responsible for the chemical properties of an element?

• Protons

• Electrons

• Neutrons

• Positrons

Answer explanation

The chemical properties of an element are determined by the number and arrangement of electrons in its atoms. Electrons are the subatomic particles that occupy the space around the nucleus of an atom and are involved in chemical reactions and the formation of chemical bonds. Therefore, electrons are responsible for the chemical properties of an element.

An atom that has gained or lost electrons and has an electric charge is called a:

• Molecule

• Ion

• Isotope

• Compound

Answer explanation

An atom becomes an Ion when it gains or loses electrons, resulting in an electric charge. This is because the number of protons and electrons are no longer equal. Molecules, Isotopes, and Compounds do not necessarily have an electric charge, making Ion the correct answer to the question.

Which of the following particles has a negative charge?

• Proton

• Neutron

• Electron

• Alpha particle

Answer explanation

The question asks about the particle with a negative charge. Among the given options, the electron is the only particle that carries a negative charge. Protons have a positive charge, neutrons are neutral, and alpha particles are positively charged.

The number of protons in an atom is also known as the:

• Atomic number

• Mass number

• Atomic mass

• Isotope number

Answer explanation

The atomic number of an atom is defined as the number of protons in its nucleus. This is a fundamental property that defines the chemical characteristics of an atom and identifies it as a particular element. Therefore, the correct answer to the question is 'Atomic number'.

Isotopes of an element have the same number of:

• Electrons

• Protons

• Neutrons

• Valence electrons

Answer explanation

Isotopes of an element have the same number of protons but different numbers of neutrons. This is what makes them isotopes of the same element. They have the same atomic number (number of protons), but different mass numbers due to the varying number of neutrons. Electrons or valence electrons do not determine isotopes.

Which of the following is an isotope of hydrogen?

• Deuterium

• Helium

• Lithium

• Oxygen

Answer explanation

Deuterium is an isotope of hydrogen. Isotopes are variants of a particular chemical element which differ in neutron number, and are named after the element itself. In this case, deuterium is a variant of hydrogen, hence it is an isotope of hydrogen. The other options, Helium, Lithium, and Oxygen are not isotopes of hydrogen.

The valence electrons of an atom are located in the:

• First energy level

• Second energy level

• Innermost energy level

• All energy levels

Answer explanation

The valence electrons of an atom are located in the second energy level. These are the electrons that are involved in chemical reactions and bonding. The first energy level is too close to the nucleus to be involved in bonding, while the innermost level is too far away. All energy levels do not contain valence electrons, as some levels are filled with core electrons.

Elements in the same family on the periodic table have the same —

• number of neutrons

• number of valence electrons

• atomic mass

• number of protons

Answer explanation

Elements in the same family on the periodic table share the same number of valence electrons. Valence electrons are the electrons in the outermost shell of an atom and determine an element's chemical properties. Therefore, elements in the same family have similar chemical behaviors.

How many valence electrons does an element in Group 17 (halogens) have?

• 1

• 2

• 7

• 8

Answer explanation

The elements in Group 17, also known as halogens, have seven valence electrons. Valence electrons are the electrons in the outermost shell of an atom and are involved in forming chemical bonds with other atoms. In this case, the correct answer is 7.

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

• 2

• 4

• 6

• 8

Answer explanation

The second energy level of an atom can hold a maximum of 8 electrons. This is based on the formula 2n^2, where n represents the energy level. For the second energy level (n=2), the formula gives 2*(2^2) = 8.