Chemistry Chapter 3 Part 2: Matter, Properties, Changes, and Energy

Q13. Can you identify a pure substance, element, compound, mixture, homogeneous mixture, and/or heterogeneous mixture from a molecular view diagram?

• Pure substance: Matter with a fixed composition (element or compound).

• Element: Substance made of only one type of atom.

• Compound: Substance made of two or more types of atoms chemically bonded.

• Mixture: Physical blend of two or more substances.

• Homogeneous mixture: Uniform composition throughout (solution).

• Heterogeneous mixture: Non-uniform composition; visibly different parts.

Step-by-Step Guidance

1. Examine the diagram for the types and arrangements of particles (atoms or molecules).

2. Determine if all particles are identical (element), two or more types bonded together (compound), or a mix of different particles (mixture).

3. If a mixture, check if the distribution is uniform (homogeneous) or not (heterogeneous).

Q14. Can you define and identify a physical property of matter?

• Physical property: A characteristic that can be observed or measured without changing the substance's identity (e.g., color, melting point, density).(e.g., boiling point, mass, volume).

Q15. Can you define and identify a chemical property of matter?

• Chemical property: A characteristic that describes a substance's ability to change into a different substance (e.g., flammability, reactivity, ability to rust, combustibility).

Q16. Can you explain the difference between physical property and chemical property of matter?

• Physical property: Observed without changing identity.

• Chemical property: Observed only when a substance undergoes a chemical change.

Q17. Can you define and identify a physical change of matter?

• Physical change: A change in state or appearance without changing composition (e.g., melting, freezing, dissolving).

• (e.g., boiling water, tearing paper).

Q18. Can you define and identify a chemical change of matter?

This question tests your ability to recognize when a substance is transformed into a new substance.

• Chemical change: A process where one or more substances are converted into new substances (e.g., burning, rusting).

Q19. Can you explain the difference between physical change and chemical change of matter?

• Physical change: No new substance formed. Physical changes are reversible by physical means.

• Chemical change: New substance(s) formed. Chemical changes invold bonds changing.

Q20. Can you identify a physical change or chemical change of matter from molecular view diagrams?

• Physical change: Molecules themselves do not change, only their arrangement or state.

• Chemical change: Molecules are broken apart or formed into new molecules.

• melting= physical; rusting, burning= chemical

Q21. Can you define energy?

• Energy: The capacity to do work or produce heat.

Q22. Can you define kinetic energy?

• Kinetic energy (KE): Energy due to motion. (e.g., moving car, flowing water).

Formula:

$KE = \frac{1}{2}mv^2$

• $m$ = mass (kg)

• $v$ = velocity (m/s)

Q23. Can you define potential energy?

• Potential energy (PE): Stored energy due to position or composition. (e.g., stretched spring, water behind a dam).

Formula (gravitational potential energy):

$PE = mgh$

• $m$ = mass (kg)

• $g$ = acceleration due to gravity (9.8 m/s2)

• $h$ = height (m)

Q24. Can you explain the difference between kinetic and potential energy?

• Kinetic energy: Energy of motion.

• Potential energy: Stored energy due to position or arrangement.