Chemistry

Question 1

What is the difference between pure substance and a mixture?

Answer 1

🔹 Pure Substance
A pure substance is made of only one type of particle (atom or molecule) throughout.

✅ Characteristics:
Fixed composition

• Cannot be separated by physical means
• Has consistent properties (melting point, boiling point, etc.)

🧪 Examples:
Element: Oxygen (O₂), Gold (Au), Iron (Fe)
Compound: Water (H₂O), Salt (NaCl), Carbon dioxide (CO₂)

🔸 Mixture
A mixture is made of two or more different substances that are not chemically combined.

✅ Characteristics:
Variable composition

• Can be separated by physical methods (filtration, evaporation, etc.)
• Properties can vary

🧪 Examples:
- Homogeneous mixture (solution): Saltwater, air, vinegar
- Heterogeneous mixture: Salad, oil and water, sand and iron filings (You can see individual parts)

Question 2

Physical VS chemical change

Answer 2

Physical-
Nothing new created
Same particles before and after

Examples:
Melting ice
Tearing paper
Dissolving sugar in water

Chemical-
New thing made

Examples:
Burning wood
Rusting iron
Baking a cake

Question 3

What are the four indicators of chemical change?

Answer 3

1. Color change
2. Release of energy usually in the form of light/heat
3. Formation of a gas or liquid
4. Noticeable change in smell

Question 4

What does Malleability mean

Answer 4

Ability to change

Question 5

What does Ductility mean

Answer 5

Ability to be stretched

Question 6

Difference between a period and a group in the periodic table

Answer 6

Period; Across

Group; Down

Question 7

Exothermic-

Answer 7

Heat being released

Question 9

What is an ionic compound

Answer 9

A compound formed when a metal and non-metal combine with eachother