SCIENCE EXAM REVIEW GR.9 (TEACHER PACKAGE)

What is matter?

Anything with mass and volume.

What are the two main categories of matter?

Pure substances and mixtures.

Define element.

A pure substance made of only one type of atom, cannot be broken down physically or chemically.

Provide examples of elements.

Oxygen gas ($O_2$), Gold ($Au$), Helium ($He$).

Define compound.

A pure substance made of two or more different elements chemically bonded in a fixed ratio.

Provide examples of compounds.

Water ($H_2O$), Carbon Dioxide ($CO_2$), Sodium Chloride ($NaCl$).

What is a homogeneous mixture?

A physical blend of substances that looks identical throughout (single phase).

Provide examples of homogeneous mixtures.

Saltwater, Apple juice, Clean air, Brass (alloy).

What is a heterogeneous mixture?

A physical blend of substances where different parts/components are visibly distinct.

Provide examples of heterogeneous mixtures.

Chocolate chip cookie, Muddy water, Oil & vinegar salad dressing.

Define physical property.

A characteristic of a substance that can be observed or measured without changing its chemical identity.

Define chemical property.

A characteristic that describes how a substance reacts with another substance to form something entirely new.

Provide examples of physical properties.

State of matter, color, density, melting point, boiling point, solubility, luster, malleability, conductivity.

Provide examples of chemical properties.

Combustibility, reactivity with water/acid, stability, toxicity, flammability.

List the first 20 elements and their symbols.

1. Hydrogen $H$ 2. Helium $He$ 3. Lithium $Li$ 4. Beryllium $Be$ 5. Boron $B$ 6. Carbon $C$ 7. Nitrogen $N$ 8. Oxygen $O$ 9. Fluorine $F$ 10. Neon $Ne$ 11. Sodium $Na$ 12. Magnesium $Mg$ 13. Aluminum $Al$ 14. Silicon $Si$ 15. Phosphorus $P$ 16. Sulfur $S$ 17. Chlorine $Cl$ 18. Argon $Ar$ 19. Potassium $K$ 20. Calcium $Ca$.

What is an ionic compound?

Formed when a metal transfers electrons to a non-metal, creating charged ions that attract one another.

What are the properties of ionic compounds?

High melting points, form crystal lattices, conduct electricity when dissolved in water.

What is a molecular (covalent) compound?

Formed when two or more non-metals share valence electrons to achieve stability.

What are the properties of molecular compounds?

Lower melting points and do not conduct electricity.

What is the difference between atomic number and atomic mass?

Atomic number ($Z$) is the number of protons in the nucleus, while atomic mass ($A$) is the average mass of an element's atoms, equal to the total number of protons and neutrons.

Describe the Bohr-Rutherford model of an atom.

Nucleus contains protons and neutrons, electrons are located in energy levels around the nucleus.

What is Ohm's Law?

The relationship between current ($I$), voltage ($V$), and resistance ($R$): $I = \frac{V}{R}$.

Define bioaccumulation.

The buildup of a toxic chemical within the body of a single organism over its lifetime.

Define biomagnification.

The increase in concentration of a toxic chemical as it moves up a food chain from one trophic level to the next.

What is the difference between renewable and non-renewable energy sources?

Renewable energy sources can be replenished naturally (e.g., solar, wind), whereas non-renewable energy sources exist in finite amounts and can be depleted (e.g., fossil fuels).

What are the phases of the moon?

New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Third Quarter, Waning Crescent.

What is a food chain?

A linear path showing how energy is transferred from one organism to another as they eat.

What is a food web?

A complex diagram showing many interconnected food chains within an ecosystem.

What are decomposers?

Organisms that break down dead matter, returning nutrients to the soil (e.g., fungi, bacteria).

What is the function of producers?

To make their own food via photosynthesis (e.g., grass, flowers, trees).

What is the role of herbivores in an ecosystem?

Animals that eat only plants (e.g., grasshopper, rabbits).

What is the role of carnivores in an ecosystem?

Animals that eat other animals (e.g., frog, snake, wolf).

What is the difference between primary and secondary energy sources?

Primary energy sources are raw energy found in nature (e.g., fossil fuels), while secondary sources are produced by transforming primary energy (e.g., electricity).

Explain the carbon cycle.

Carbon moves through living and non-living parts of ecosystems via processes like photosynthesis, respiration, decomposition, and combustion.

What defines a spiral galaxy?

A galaxy with a central bulge and flat, rotating spiral arms of gas, dust, and young stars (e.g., the Milky Way).

What is a solar eclipse?

An event where the Moon passes directly between the Sun and Earth, blocking sunlight from reaching Earth.

What is a lunar eclipse?

An event where Earth passes directly between the Sun and Moon, casting a shadow over the Moon.

What causes tides?

The rising and falling of ocean waters caused by gravitational pull of the Moon and the Sun on Earth.

What is the life cycle of a star?

Begins as a stellar nebula, evolves to a protostar, ignites nuclear fusion to become a main sequence star, then dies based on its mass.

What is the Hertzsprung-Russell diagram?

A plot of stars based on their luminosity and surface temperature, showing different stages of star life cycles.