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What are the reactants in a chemical reaction?
What are the reactants in a chemical reaction?
Physical changes always result in the formation of new substances.
Physical changes always result in the formation of new substances.
False
What is the scientific term for burning?
What is the scientific term for burning?
combustion
A substance made up of only one type of element or compound is called a ___.
A substance made up of only one type of element or compound is called a ___.
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Match the following types of chemical changes with their descriptions:
Match the following types of chemical changes with their descriptions:
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What happens to energy during a chemical reaction?
What happens to energy during a chemical reaction?
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Changing the subscripts in a chemical formula does not change the substance it represents.
Changing the subscripts in a chemical formula does not change the substance it represents.
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What is neutral pH indicated by on the universal indicator pH chart?
What is neutral pH indicated by on the universal indicator pH chart?
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What occurs when light is refracted as it enters a prism?
What occurs when light is refracted as it enters a prism?
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All elements in Group 0 of the periodic table are reactive.
All elements in Group 0 of the periodic table are reactive.
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What is the definition of a refractive index?
What is the definition of a refractive index?
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The colors of the electromagnetic spectrum in order are red, orange, yellow, green, blue, indigo, and __________.
The colors of the electromagnetic spectrum in order are red, orange, yellow, green, blue, indigo, and __________.
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Match the following elements with their classification:
Match the following elements with their classification:
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What is the main characteristic of an ionic bond?
What is the main characteristic of an ionic bond?
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All metals form positively charged ions when they react.
All metals form positively charged ions when they react.
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What happens to the speed of light as it enters a medium of different density?
What happens to the speed of light as it enters a medium of different density?
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What is produced during the complete combustion of methane?
What is produced during the complete combustion of methane?
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Incomplete combustion occurs when there is an excess of oxygen available.
Incomplete combustion occurs when there is an excess of oxygen available.
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Define thermal decomposition.
Define thermal decomposition.
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An example of an _ reaction is thermal decomposition.
An example of an _ reaction is thermal decomposition.
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Match the type of reaction with its correct description:
Match the type of reaction with its correct description:
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Which of the following describes activation energy?
Which of the following describes activation energy?
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A compass needle always points towards the magnetic north pole of the Earth.
A compass needle always points towards the magnetic north pole of the Earth.
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What happens to a magnetic material when it is removed from a magnetic field?
What happens to a magnetic material when it is removed from a magnetic field?
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The reactivity series helps predict the outcomes of _ reactions.
The reactivity series helps predict the outcomes of _ reactions.
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Match the following types of magnets with their characteristics:
Match the following types of magnets with their characteristics:
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In a redox reaction, what happens to one of the substances?
In a redox reaction, what happens to one of the substances?
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The energy needed to break bonds is exothermic.
The energy needed to break bonds is exothermic.
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What is bond energy?
What is bond energy?
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When bonds are made, energy is _ to the surroundings.
When bonds are made, energy is _ to the surroundings.
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What is the formula for calculating the overall energy change in a reaction?
What is the formula for calculating the overall energy change in a reaction?
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Exothermic reactions always have a positive energy change.
Exothermic reactions always have a positive energy change.
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What happens to the magnetic field strength when the current flowing through a wire increases?
What happens to the magnetic field strength when the current flowing through a wire increases?
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An electric field is the region where an __________ force can be felt by charged objects.
An electric field is the region where an __________ force can be felt by charged objects.
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Match the following types of magnets to their descriptions:
Match the following types of magnets to their descriptions:
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Which of the following is not a way to increase the strength of a magnetic field in a solenoid?
Which of the following is not a way to increase the strength of a magnetic field in a solenoid?
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Electric field lines point toward positive charges.
Electric field lines point toward positive charges.
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What is required to break bonds in an endothermic reaction?
What is required to break bonds in an endothermic reaction?
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When a fridge magnet sticks to the fridge door, the fridge door acts as an __________ magnet.
When a fridge magnet sticks to the fridge door, the fridge door acts as an __________ magnet.
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Match the following factors to their effects on reaction rates:
Match the following factors to their effects on reaction rates:
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What happens when a permanent magnet is heated to a high temperature?
What happens when a permanent magnet is heated to a high temperature?
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Larger currents produce weaker magnetic fields.
Larger currents produce weaker magnetic fields.
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What type of metals typically make up ferrous metals?
What type of metals typically make up ferrous metals?
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The magnetic field around a solenoid is similar to that of a __________.
The magnetic field around a solenoid is similar to that of a __________.
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Match the following items to their characteristics:
Match the following items to their characteristics:
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What is the principle that allows motors to work?
What is the principle that allows motors to work?
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Sound waves can travel through a vacuum.
Sound waves can travel through a vacuum.
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What type of current allows a motor to function by reversing direction every half-turn?
What type of current allows a motor to function by reversing direction every half-turn?
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The pitch of a sound wave is related to its ______.
The pitch of a sound wave is related to its ______.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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Which of the following increases the speed of a motor?
Which of the following increases the speed of a motor?
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Sound waves travel faster through gases than through solids.
Sound waves travel faster through gases than through solids.
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What phenomenon do bats use to find their food?
What phenomenon do bats use to find their food?
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Light waves are ______ waves that do not need a medium to travel through.
Light waves are ______ waves that do not need a medium to travel through.
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Match the wave types with their characteristics:
Match the wave types with their characteristics:
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Which of these devices commonly uses a motor?
Which of these devices commonly uses a motor?
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The angle of reflection equals the angle of incidence in light waves.
The angle of reflection equals the angle of incidence in light waves.
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What happens to sound waves when they travel through a material?
What happens to sound waves when they travel through a material?
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The formula to calculate distance using sound waves is ______ = speed x time.
The formula to calculate distance using sound waves is ______ = speed x time.
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Study Notes
Pure Substances
- Pure substances consist of only one type of element or compound.
Products of Chemical Reactions
- Products of chemical reactions often have a neutral pH (green on the universal indicator scale).
Chemical Reactions
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Chemical reactions involve atoms joining to form compounds via electron transfer or sharing.
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Chemical bonds form from this electron interaction.
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Chemical reactions always result in new substances.
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Energy is conserved in chemical reactions.
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Energy is either released or absorbed during chemical reactions.
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Changes of state (e.g., melting, freezing) are physical changes that do not form new substances.
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Chemical changes (e.g., burning) are much harder to reverse than physical changes.
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Atoms are rearranged during chemical reactions, but the total number of atoms remains constant (law of conservation of mass).
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Bonds in reactants break, and new bonds form in products.
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A balanced chemical equation has the same number of each element in reactants and products.
Reactants and Products
- Reactants are the starting materials in a chemical reaction.
- Products are the substances formed in the reaction.
Balancing Chemical Equations
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Coefficients balance equations, not subscripts.
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Changing subscripts changes the substance itself (e.g., CO vs. CO2).
Identifying Chemical Reactions
- Color change, bubbling (effervescence), change in temperature, and precipitate formation are indicators of chemical reactions.
Everyday Chemical Reactions
- Rusting (iron, oxygen, water), baking, and burning are examples.
Combustion
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Combustion is the process of burning.
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Fuels are substances burned to release energy.
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Combustion is an oxidation reaction involving a fuel reacting with oxygen.
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Combustion Equation: methane + oxygen → carbon dioxide + water
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Combustion uses fuels to transfer chemical energy.
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Friction or heat can initiate combustion.
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Released thermal energy sustains combustion until fuel is exhausted.
Incomplete Combustion
- Incomplete combustion occurs with insufficient oxygen, releasing less energy and producing carbon monoxide (soot) instead of carbon dioxide.
Thermal Decomposition
- Thermal decomposition is breaking down a compound by heating it.
- Only one reactant is involved, which breaks down into two products.
Displacement Reactions
- A more reactive element displaces a less reactive element from a compound.
- The reactivity series predicts the outcome of displacement reactions.
- The displaced element becomes a pure, free element.
Oxidation and Reduction
- Oxidation is the addition of oxygen.
- Redox reactions involve one substance being oxidized and another being reduced. (losing oxygen)
- Neutralization reactions involve an acid reacting with a base to produce salt and water.
Exothermic Reactions
- Exothermic reactions release energy to their surroundings.
- Neutralization reactions and combustion are exothermic.
- The temperature increases due to the released energy.
- Products are at a lower energy level than reactants.
Endothermic Reactions
- Endothermic reactions absorb energy from their surroundings.
- Thermal decomposition and some cold packs utilize endothermic reactions.
- The temperature decreases due to energy absorption.
- Products are at a higher energy level than reactants.
Activation Energy
- Activation energy is the minimum energy needed for particles to react.
- Different reactions have different activation energy levels.
- Reaction profiles graphically illustrate energy changes during reactions.
Reaction Profiles
- Differences in reactant and product energies represent energy transferred to or from surroundings.
Magnetism
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Magnets have north and south poles.
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Magnetic forces are non-contact forces. Like poles repel and unlike poles attract.
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Permanent magnets create their own magnetic fields.
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Induced magnets become magnetic in magnetic fields and are always attracted to permanent magnets.
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Magnetic metals include iron, steel, cobalt, and nickel.
Magnetic Fields
- Magnetic fields are regions where magnets experience forces.
- Magnetic field lines show the field's direction and strength.
- Field lines go from north to south poles.
- Iron filings align with magnetic field lines.
- Compasses align with magnetic field lines to map magnetic fields.
Earth's Magnetic Field
- The Earth is a giant magnet with a north magnetic pole (actually a south magnetic pole).
- Earth's magnetic field helps compasses point North.
Bond Making and Breaking
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Breaking bonds absorbs energy (endothermic).
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Making bonds releases energy (exothermic).
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Bond energy is the energy needed to break a bond or released when a bond forms, measured in kJ/mol.
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Reactions are endothermic if bond-breaking energy > bond-forming energy, & exothermic when the reverse is true.
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Overall energy change = energy in - energy out - energy needed to break bonds - energy released to form bonds.
Electric Currents and Magnetic Fields
- Currents in wires produce magnetic fields.
- Stronger currents create stronger fields.
- Field lines are circular around the wire.
- Wire coils (solenoids) produce stronger magnetic fields.
Electromagnets
- Electromagnets are temporary magnets produced by current in a coil of wire around a magnetic core.
- Electromagnets can be turned on and off by controlling the current.
Motor Effect
- Current-carrying wires placed in magnetic fields experience forces.
- The force direction depends on the current and magnetic field directions.
- Increasing current or magnetic field strength increases the force.
- Motors utilize this effect for continuous rotation.
Generators
- Generators use movement to create electrical current.
- Motors use electrical currents to produce movement.
Sound Waves
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Sound waves are longitudinal waves produced by vibrations in a medium (e.g., air).
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Sound travels faster in solids due to tighter particle packing. Temperature also affects speed.
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Sound waves are sensed when vibrations reach an ear or other sound detection mechanism
Ultrasound
- Ultrasound has frequencies above the human hearing range.
Light Waves
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Light waves are transverse electromagnetic waves that do not require a medium.
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Light from one material reflects when it hits a boundary of another different material
Refraction
- Waves change speed and direction when moving between substances of different densities.
Dispersion
- Different colors of light refract by different amounts in prisms, separating the light into a spectrum (rainbow).
Lenses
- Convex lenses converge parallel light rays, concave lenses diverge.
Ionic Bonds
- Ions are charged particles formed by atoms losing or gaining electrons in chemical reactions.
- Ionic bonds form between oppositely charged ions.
Periodic Table
- The periodic table organizes elements based on electron configuration (number of electrons per shell).
- Groups (vertical) determine outer electron shell electrons.
- Periods (horizontal) determine the number of electron shells.
- Isotopes are atoms of the same element with different numbers of neutrons.
- Groups and periods within the table group, elements that share similar properties.
- Halogens (Group 7) are highly reactive non metals.
- Alkali metals (Group 1) are also very reactive metals
- Noble gases (Group 0) are among the least reactive of all elements.
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Description
This quiz explores the fundamental concepts of pure substances and chemical reactions. It covers topics such as the formation of compounds, energy changes during reactions, and the distinction between physical and chemical changes. Test your knowledge on the law of conservation of mass and balanced chemical equations.
