Grade 9 Science: Particle Theory of Matter

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Questions and Answers

Which subatomic particle is responsible for static electricity?

Electron (correct)

Proton

Neutron

Nucleus

What happens to an object when it gains electrons?

It becomes positively charged.

It becomes negatively charged. (correct)

It remains neutral.

It becomes radioactive.

Which of the following is NOT a method of charging objects?

Radiation (correct)

Friction

Induction

Conduction

What is the term for a material that allows electrons to flow easily?

Conductor Signup and view all the answers

What is a lightning rod designed to do?

Direct lightning strikes to the ground. Signup and view all the answers

What is the difference between direct current (DC) and alternating current (AC)?

DC flows in one direction; AC flows in multiple directions. Signup and view all the answers

What is the purpose of a switch in an electrical circuit?

Control the flow of current. Signup and view all the answers

Which of the following is NOT a part of an electrical circuit?

Grounding Signup and view all the answers

What is the relationship between voltage, current, and resistance according to Ohm's Law?

Voltage is directly proportional to current and resistance. Signup and view all the answers

What is the unit of measurement for electric current?

Amperes (A) Signup and view all the answers

Which type of circuit provides multiple paths for electrons to flow?

Parallel circuit Signup and view all the answers

If one light bulb in a series circuit burns out, what happens to the other light bulbs?

They burn out too. Signup and view all the answers

What is the atomic number of an element?

The number of protons in the nucleus Signup and view all the answers

What is the difference between a molecule and an ion?

Molecules are neutral; ions are charged. Signup and view all the answers

What is the difference between a cation and an anion?

Cations are positive ions; anions are negative ions. Signup and view all the answers

What is the atomic mass of an atom?

The total number of protons and neutrons Signup and view all the answers

What is the difference between a physical property and a chemical property?

Physical properties can be observed without changing the substance's chemical composition; chemical properties can only be observed by changing the substance's chemical composition. Signup and view all the answers

Which statement accurately describes particles in matter?

Particles are in constant motion and have spaces between them. Signup and view all the answers

What defines a pure substance?

Contains one type of particle. Signup and view all the answers

What type of mixture is trail mix classified as?

Mechanical (heterogeneous) mixture Signup and view all the answers

Which property of matter can be observed without changing the substance?

Melting point Signup and view all the answers

What is an example of a chemical change?

Rusting of iron Signup and view all the answers

How is density calculated?

Mass divided by volume Signup and view all the answers

Which group contains very reactive non-metals that form salts?

Halogens Signup and view all the answers

What charge does a proton carry?

Positive charge Signup and view all the answers

What is one main difference between direct current (DC) and alternating current (AC)?

AC varies the direction of electron flow. Signup and view all the answers

Which statement is true about series circuits?

They have only one path for current to flow. Signup and view all the answers

Which of the following best describes a star?

A luminous celestial object generating energy by nuclear fusion. Signup and view all the answers

What defines a planet in the context of celestial objects?

It must orbit a star and is large enough to be rounded by gravity. Signup and view all the answers

What is the primary cause of seasons on Earth?

The tilt of Earth's axis. Signup and view all the answers

What is the term for cooler, darker areas on the Sun's surface?

Sunspots Signup and view all the answers

Which of the following accurately describes the term 'orbit'?

The curved path an object takes around another due to gravity. Signup and view all the answers

Which factors are primarily involved in gravitational force?

Mass of the objects and distance between them. Signup and view all the answers

What is the phenomenon that occurs when the Moon blocks sunlight from reaching the Earth?

Solar eclipse Signup and view all the answers

What is the main feature of a parallel circuit?

If one load fails, the rest continue to operate. Signup and view all the answers

What term describes a celestial body that has not cleared its orbit of debris?

Dwarf planet Signup and view all the answers

What is the distance represented by one astronomical unit (AU)?

About 150 million kilometers. Signup and view all the answers

What is the largest structure in the universe?

Universe Signup and view all the answers

Study Notes

Particle Theory of Matter

All matter is composed of tiny particles.
These particles are constantly moving.
Particles attract each other.
Particles have spaces between them.
Heating increases particle speed and energy, potentially breaking bonds, leading to phase changes (e.g., ice to water).

Classification of Matter

Pure Substances: Contain only one type of particle.
- Elements: Examples include oxygen (O₂) and gold (Au).
- Compounds: Examples include water (H₂O) and carbon dioxide (CO₂).
Mixtures: Contain more than one type of particle.
- Mechanical Mixtures (Heterogeneous): Distinct parts are visible (e.g., trail mix, sand and iron filings).
- Solutions (Homogeneous): Uniform appearance, particles evenly distributed (e.g., saltwater, vinegar).

Properties of Matter

Physical Property: Characteristics observed without changing the substance's composition.
- Qualitative: Describes qualities (e.g., color, texture, state).
- Quantitative: Describes measurable quantities (e.g., density, melting point, viscosity).
Chemical Property: Describes the substance's ability to undergo a chemical change, forming new substances (e.g., flammability, reactivity).

Changes in Matter

Physical Change: No new substance is formed; it alters the physical state, shape, or size (e.g., melting ice, breaking a stick).
Chemical Change: New substances are created; recognizable signs include:
- Color change
- Gas production (bubbles)
- Precipitate formation (solid in a liquid)
- Heat or light release/absorption
- Irreversibility (e.g., rusting, burning wood).

Density

Definition: Mass per unit volume.
Formula: Density = Mass ÷ Volume
Units: g/cm³ or g/mL.
Example: A sample with 50 g and 25 cm³ has a density of 2 g/cm³.

The Periodic Table

Key Groups:
- Metals: Shiny, good conductors, malleable (e.g., aluminum).
- Non-Metals: Dull, poor conductors, brittle (e.g., sulfur).
- Metalloids: Properties of both metals and non-metals (e.g., silicon).
Families (Groups): Elements with similar chemical properties.
- Alkali Metals (Group 1): Highly reactive, soft, 1 valence electron.
- Alkaline Earth Metals (Group 2): Reactive, 2 valence electrons.
- Halogens (Group 17): Very reactive non-metals, form salts.
- Noble Gases (Group 18): Unreactive, full outer energy levels.
Trends: Properties change progressively across periods (rows) and exhibit similarities within groups (columns).

Atoms and Subatomic Particles

Subatomic Particles:
- Proton: Positive charge, in the nucleus, mass ≈ 1 amu.
- Neutron: Neutral charge, in the nucleus, mass ≈ 1 amu.
- Electron: Negative charge, outside the nucleus, negligible mass.
Atomic Number: Number of protons (and electrons in a neutral atom).
Atomic Mass: Number of protons + neutrons.
Example (Carbon): Atomic number 6 (6 protons, 6 electrons); Atomic mass 12 (6 protons + 6 neutrons).

Bohr-Rutherford Diagrams

Drawing Steps:
1. Place protons and neutrons in the nucleus.
2. Distribute electrons in shells (2 in first, 8 in second, etc.)

Molecules and Ions

Molecule: Two or more atoms bonded together (e.g., H₂O, O₂).
Ion: Charged particle formed when an atom gains/loses electrons.
- Cation: Positive ion (loses electrons).
- Anion: Negative ion (gains electrons).

Static Electricity

Static Electricity: Buildup of electric charge on a material's surface.
Electron Movement: Only electrons can move between objects.
Neutral Objects: Equal numbers of protons and electrons.
Charging Methods:
- Friction: Rubbing transfers electrons.
- Conduction: Direct contact transfers electrons.
- Induction: Rearranging electrons without contact.

Electric Discharge and Lightning

Electric Discharge: Rapid electron transfer.
- Example: Spark from doorknob.
Lightning: Large discharge in clouds, usually caused by air friction.
Lightning Rods: Conduct lightning safely to the ground.
Dangers of Lightning: High voltage and heat.

Conductors and Insulators

Conductor: Allows easy electron flow (e.g., metals).
Insulator: Resists electron flow (e.g., rubber, plastic).

Grounding

Grounding: Connecting a charged object to the earth to neutralize the charge by transferring electrons.

Current Electricity

Electrical Energy: Energy from electron movement.
Electric Cells: Convert chemical energy to electrical energy (e.g., batteries).
Direct Current (DC): Electrons flow one way (batteries).
Alternating Current (AC): Electrons change direction (wall outlets).

Electrical Circuits

Circuit Components:
- Energy source (e.g., battery)
- Load (e.g., lamp, motor)
- Conducting wires
- Switch
Circuits:
- Series: One path, all loads share current, failure stops the circuit.
- Parallel: Multiple paths, loads independent, failure doesn't stop the entire circuit.

Measuring Electricity

Electric Current (I): Electron flow, measured in amperes (A) by an ammeter.
Potential Difference (Voltage): Energy difference between circuit points, measured in volts (V) by a voltmeter.
Resistance (R): Opposition to current, measured in ohms (Ω).
Ohm’s Law: V = I × R

Astronomy

Celestial Objects: Objects in space (planets, stars, moons, comets).
Stars: Luminous objects generating energy via nuclear fusion.
Planets: Orbit stars, are massive enough to be rounded by gravity, and have cleared their orbits.
Solar System: Star (e.g., Sun) and all objects orbiting it.
Galaxy: A massive system of stars, planets, gas, and dust.
Universe: Everything that exists (galaxies, stars, matter).
Orbit: Path a celestial object takes around another due to gravity.
Electromagnetic Radiation: Energy waves like light and radio waves.
Solar Phenomena:
- Sunspots: Dark areas on the Sun from magnetic activity.
- Solar Flares: Sudden bursts of solar energy.
- Prominences: Large, bright gas loops.
- Aurora Borealis: Northern Lights from solar particles interacting with Earth's atmosphere.
Solar System Objects:
- Astronomical Unit (AU): Average Earth-Sun distance (150 million km).
- Dwarf Planet: Orbits the Sun but hasn't cleared its orbit (e.g., Pluto).
- Asteroid: Small, rocky object orbiting the Sun.
- Meteoroid: Small rock or particle in space.
- Comet: Ice, rock, and dust with a tail when near the Sun.
Celestial Motion:
- Gravity: Attraction between objects with mass.
- Solstices: Extreme points in Earth's orbit, causing longest or shortest days.
- Equinoxes: Day and night are equal length.
- Lunar Cycle/Phases: Moon's changing appearance.
- Eclipses: Solar (Sun blocked by Moon) and Lunar (Earth blocks Sun from Moon).
- Tides: Ocean level changes from Moon's and Sun's gravity.
Earth's Motion:
- Rotation: Spinning of Earth on its axis (day and night).
- Revolution: Earth orbiting the Sun (seasons).
Models of the Solar System:
- Geocentric: Earth at the center.
- Heliocentric: Sun at the center.
Constellations: Groups of stars forming patterns.

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Description

Test your understanding of the Particle Theory of Matter and the classification of different types of matter. This quiz covers pure substances, mixtures, and the properties of matter. It's designed for Grade 9 science students looking to reinforce their knowledge on these fundamental concepts.