Q1. Draw and label a simplified model of an atom.

Background

Topic: Atomic Structure

This question tests your understanding of the basic components of an atom and their arrangement.

Key Terms:

• Atom: The smallest unit of matter that retains the properties of an element.

• Proton: Positively charged particle found in the nucleus.

• Neutron: Neutral particle found in the nucleus.

• Electron: Negatively charged particle found in electron shells surrounding the nucleus.

Step-by-Step Guidance

1. Start by drawing a central circle to represent the nucleus.

2. Inside the nucleus, label protons (p+) and neutrons (n0).

3. Draw one or more concentric circles around the nucleus to represent electron shells.

4. Place electrons (e-) on these shells, spaced out to show their movement.

5. Label each part clearly: nucleus, protons, neutrons, electrons, and electron shells.

Try sketching your own atom before checking an example!

Q2. Define and differentiate: element/compound; neutron/proton/electron; atomic number/mass number; covalent bond/ionic bond/hydrogen bond; isotope/ion.

Background

Topic: Basic Chemistry Terminology

This question tests your ability to define and distinguish between fundamental chemistry terms relevant to biology.

Key Terms:

• Element: A substance made of only one type of atom.

• Compound: A substance made of two or more elements chemically bonded.

• Neutron, Proton, Electron: Subatomic particles with different charges and locations.

• Atomic Number: Number of protons in an atom.

• Mass Number: Sum of protons and neutrons.

• Covalent Bond: Sharing of electrons between atoms.

• Ionic Bond: Transfer of electrons, resulting in charged ions.

• Hydrogen Bond: Weak attraction between a hydrogen atom and another electronegative atom.

• Isotope: Atoms of the same element with different numbers of neutrons.

• Ion: Atom or molecule with a net charge due to loss or gain of electrons.

Step-by-Step Guidance

1. Write definitions for each term, focusing on their unique characteristics.

2. For each pair or set, identify what makes them similar and what makes them different.

3. Use examples to clarify differences (e.g., water as a compound, hydrogen as an element).

4. For bonds, describe how electrons are involved in each type.

5. For isotope vs. ion, explain how each is formed and their properties.

Try writing your own definitions and comparisons before checking below!

Q3. Explain how atomic number, mass number, and number of neutrons relate. If you know two, how can you find the third?

Background

Topic: Atomic Structure Calculations

This question tests your understanding of how to use atomic and mass numbers to determine the number of neutrons in an atom.

Key Formula:

Step-by-Step Guidance

1. Identify the atomic number (number of protons).

2. Identify the mass number (protons + neutrons).

3. Use the formula above to solve for the unknown value.

4. If you know atomic number and mass number, subtract atomic number from mass number to get neutrons.

5. If you know mass number and neutrons, subtract neutrons from mass number to get atomic number.

Try applying the formula to a sample atom before revealing the answer!

Q4. Find information on a periodic table (element name/symbol, atomic number, etc.).

Background

Topic: Periodic Table Usage

This question tests your ability to read and interpret the periodic table to find basic information about elements.

Key Terms:

• Element Name: The full name of the element (e.g., Carbon).

• Symbol: One or two-letter abbreviation (e.g., C).

• Atomic Number: Number of protons (e.g., 6 for Carbon).

Step-by-Step Guidance

1. Locate the element on the periodic table.

2. Read the symbol, usually in large letters.

3. Find the atomic number, typically above or below the symbol.

4. Check for other information, such as atomic mass.

Try looking up an element on a periodic table before checking below!

Q5. Compare and contrast two isotopes of an element.

Background

Topic: Isotopes

This question tests your understanding of what makes isotopes similar and different.

Key Terms:

• Isotope: Atoms of the same element with different numbers of neutrons.

Step-by-Step Guidance

1. Choose an element (e.g., Carbon).

2. Identify two isotopes (e.g., Carbon-12 and Carbon-14).

3. Compare their atomic numbers (same for both).

4. Contrast their mass numbers (different due to neutrons).

5. Discuss any differences in stability or radioactivity.

Try comparing two isotopes before checking below!

Q6. Determine how many electrons are in the outer shell (valence shell) of a given atom.

Background

Topic: Electron Configuration

This question tests your ability to use the periodic table to find the number of valence electrons.

Key Terms:

• Valence Electrons: Electrons in the outermost shell.

• Group Number: Often indicates number of valence electrons for main group elements.

Step-by-Step Guidance

1. Find the element's position on the periodic table.

2. Identify its group number (for main group elements).

3. Use the group number to determine valence electrons (e.g., Group 1 = 1 valence electron).

4. For transition metals, check electron configuration for accuracy.

Try finding valence electrons for an element before checking below!

Q7. Draw a single water molecule, labeling atoms and covalent bonds. Add two other water molecules nearby, showing hydrogen bonds.

Background

Topic: Molecular Structure and Bonding

This question tests your ability to represent water's structure and the interactions between molecules.

Key Terms:

• Water Molecule: H2O, two hydrogens covalently bonded to oxygen.

• Covalent Bond: Strong bond within the molecule.

• Hydrogen Bond: Weak bond between molecules.

Step-by-Step Guidance

1. Draw one oxygen atom (O) and two hydrogen atoms (H).

2. Connect H to O with lines to show covalent bonds.

3. Repeat for two more water molecules nearby.

4. Use dashed lines to show hydrogen bonds between the hydrogen of one molecule and the oxygen of another.

5. Label all atoms and bonds clearly.

Try sketching the molecules and bonds before checking below!

Q8. List emergent properties of water. Explain these at a molecular level, relating to polarity or hydrogen bonding. Give biological examples.

Background

Topic: Properties of Water

This question tests your understanding of water's unique properties and their biological significance.

Key Terms:

• Emergent Properties: Characteristics that arise from molecular interactions.

• Polarity: Uneven charge distribution in water.

• Hydrogen Bonding: Causes cohesion, adhesion, high specific heat, etc.

Step-by-Step Guidance

1. List properties: cohesion, adhesion, high specific heat, evaporative cooling, ice floats, solvent ability.

2. Explain how polarity and hydrogen bonding cause each property.

3. Give a biological example for each (e.g., water transport in plants for cohesion).

4. Describe the molecular interactions involved.

Try listing and explaining properties before checking below!

Q9. Distinguish between cohesion and adhesion.

Background

Topic: Water Properties

This question tests your understanding of how water interacts with itself and other substances.

Key Terms:

• Cohesion: Attraction between water molecules.

• Adhesion: Attraction between water and other substances.

Step-by-Step Guidance

1. Define cohesion and adhesion.

2. Describe the molecular basis (hydrogen bonding for cohesion).

3. Give examples (e.g., water droplets for cohesion, water climbing plant walls for adhesion).

Try distinguishing these terms before checking below!

Q10. Explain the relationships of a solute, a solvent, and a solution.

Background

Topic: Solutions and Mixtures

This question tests your understanding of how substances mix to form solutions.

Key Terms:

• Solute: Substance dissolved.

• Solvent: Substance doing the dissolving.

• Solution: Homogeneous mixture of solute and solvent.

Step-by-Step Guidance

1. Define solute, solvent, and solution.

2. Describe how a solute dissolves in a solvent.

3. Give an example (e.g., salt in water).

Try explaining these relationships before checking below!

Q11. Distinguish between hydrophobic and hydrophilic substances. Decide which a substance is based on its chemistry.

Background

Topic: Chemical Properties of Molecules

This question tests your ability to classify substances based on their interaction with water.

Key Terms:

• Hydrophobic: Repels water; nonpolar.

• Hydrophilic: Attracts water; polar or charged.

Step-by-Step Guidance

1. Define hydrophobic and hydrophilic.

2. Describe how molecular structure (polarity) affects water interaction.

3. Use examples (e.g., oil is hydrophobic, salt is hydrophilic).

4. Analyze a substance's structure to decide its classification.

Try classifying a substance before checking below!

Q12. What ions result when water dissociates?

Background

Topic: Water Chemistry

This question tests your understanding of water's dissociation and the ions produced.

Key Formula:

Step-by-Step Guidance

1. Write the dissociation equation for water.

2. Identify the ions produced: hydrogen ion and hydroxide ion.

3. Describe their charges and roles in pH.

Try writing the equation and identifying ions before checking below!

Q13. What is the pH scale based on? What are acids and bases? How do pH units relate to powers of ten?

Background

Topic: Acids, Bases, and pH

This question tests your understanding of pH, acids, bases, and logarithmic relationships.

Key Formula:

Step-by-Step Guidance

1. Define pH and its mathematical basis (logarithm of hydrogen ion concentration).

2. Explain what acids and bases are (acids donate protons, bases accept).

3. Describe how a change in pH by one unit means a tenfold change in .

4. Calculate the difference in proton concentration for a two- or three-unit change.

Try calculating pH changes before checking below!

Q14. What’s the effect of a buffer? Why are buffers important for organisms?

Background

Topic: Buffer Systems

This question tests your understanding of how buffers maintain pH stability in biological systems.

Key Terms:

• Buffer: Substance that resists changes in pH.

Step-by-Step Guidance

1. Define what a buffer is and how it works (absorbs excess H+ or OH-).

2. Explain why pH stability is important for biological processes.

3. Give examples of biological buffers (e.g., blood bicarbonate system).

Try explaining buffer effects before checking below!