Chapter 2 Part 1: Microbiology Chemistry & Bonds Study Guide

Q1. A scientist discovers two atoms with the same atomic number but different atomic masses. These atoms are most accurately described as:

Background

Topic: Atomic Structure & Isotopes

This question tests your understanding of how atoms of the same element can differ in mass due to differences in their subatomic particles.

Key Terms:

• Atomic number: Number of protons in the nucleus of an atom.

• Atomic mass: Total number of protons and neutrons.

• Isotopes: Atoms with the same number of protons but different numbers of neutrons.

Step-by-Step Guidance

1. Recall that the atomic number defines the element and is equal to the number of protons.

2. Understand that atomic mass changes when the number of neutrons changes, not protons.

3. Review the definitions of ions, molecules, isotopes, and compounds to determine which term fits atoms with the same atomic number but different masses.

Try solving on your own before revealing the answer!

Q2. Which statement best explains why isotopes remain the same element?

Background

Topic: Isotopes & Element Identity

This question focuses on what determines the identity of an element, even when isotopes exist.

Key Terms:

• Isotope: Same element, different number of neutrons.

• Element identity: Determined by the number of protons.

Step-by-Step Guidance

1. Review what makes an atom a specific element (hint: atomic number).

2. Consider which subatomic particle count must remain the same for isotopes of an element.

3. Compare the answer choices to see which one matches this requirement.

Try solving on your own before revealing the answer!

Q3. A neutral carbon atom always contains:

Background

Topic: Atomic Structure

This question tests your knowledge of the basic structure of a neutral atom, specifically carbon.

Key Terms:

• Neutral atom: Number of protons equals number of electrons.

• Carbon: Atomic number 6.

Step-by-Step Guidance

1. Recall the atomic number of carbon and what it represents.

2. Determine how many protons and electrons a neutral carbon atom must have.

3. Check the answer choices for the correct combination.

Try solving on your own before revealing the answer!

Q4. Which particle contributes the least to an atom's atomic weight?

Background

Topic: Subatomic Particles & Atomic Mass

This question asks you to compare the relative masses of protons, neutrons, and electrons.

Key Terms:

• Proton: Mass ≈ 1 atomic mass unit (amu)

• Neutron: Mass ≈ 1 amu

• Electron: Mass ≈ 1/1836 amu (very small)

Step-by-Step Guidance

1. Recall the approximate masses of protons, neutrons, and electrons.

2. Consider which particle's mass is negligible when calculating atomic weight.

3. Identify the correct answer based on these comparisons.

Try solving on your own before revealing the answer!

Q5. Which statement regarding valence electrons is TRUE?

Background

Topic: Valence Electrons & Chemical Reactivity

This question tests your understanding of the role of valence electrons in chemical bonding and reactivity.

Key Terms:

• Valence electrons: Electrons in the outermost shell of an atom.

• Chemical reactivity: Determined by valence electrons.

Step-by-Step Guidance

1. Recall where valence electrons are located in an atom.

2. Think about how valence electrons affect chemical interactions and bonding.

3. Evaluate each statement to find the one that is accurate about valence electrons.

Try solving on your own before revealing the answer!

Q6. An atom loses one electron. What immediately happens?

Background

Topic: Ions & Atomic Charge

This question tests your understanding of how atoms become ions and how their charge changes.

Key Terms:

• Ion: An atom with a net electric charge due to loss or gain of electrons.

• Cation: Positively charged ion (loss of electron).

• Anion: Negatively charged ion (gain of electron).

Step-by-Step Guidance

1. Recall what happens to the charge of an atom when it loses an electron.

2. Determine whether the atom becomes positively or negatively charged.

3. Check which answer choice matches this outcome.

Try solving on your own before revealing the answer!

Q7. Which type of bond forms when electrons are transferred completely from one atom to another?

Background

Topic: Chemical Bonds

This question tests your knowledge of the different types of chemical bonds and how they form.

Key Terms:

• Ionic bond: Formed by complete transfer of electrons.

• Covalent bond: Formed by sharing electrons.

• Hydrogen bond: Weak attraction between partial charges.

Step-by-Step Guidance

1. Review the definitions of ionic, covalent, and hydrogen bonds.

2. Identify which bond involves the complete transfer of electrons.

3. Match the correct bond type to the description in the question.

Try solving on your own before revealing the answer!