Concept Review

Energy

What is Energy?

Thermal expansion

Energy is the ability to do work

Endothermic and Exothermic Reactions

Thermal expansion in metals

the Law of Conservation of Energy

Energy can neither be created nor destroyed, it can only be transferred from one form to another

Endothermic Reactions

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Energy Flow in an Ecosystem

Exothermic Reactions

Chemical reactions in which the reactants absorb heat energy from its surroundings.

The only thing that changes is the form in which energy appears

Heat and Temperature

Energy Transformations

Chemical reactions in which the reactants release energy in the form of heat and light to its surroundings.

Examples of energy changing form

The total energy doesn't change when an energy transformation occurs.

Types of heat tranfer

What is temperature

What is heat

Food Chain

Food Pyramid

Examples: burning a candle, making ice cubes.

Examples: melting ice cubes, cooking / baking, photosynthesis.

The reactants have more chemical energy than its products, as energy and heat is lost in the process.

General Info

What is Work?

The transfer of energy to matter by a force that causes the matter to move in the direction of the force

Heat is the form of energy that is transferred between systems or objects with different temperatures. Heat is also known as thermal energy. Heat is typically measured in Btu, calories or joules.

In televisions, the electrical energy is converted into sound and light energy while electrical energy is converted into sound in the case of radios

Food Web

In ecology, energy flow refers to the flow of energy through a food chain.

Each organism belongs to a 'trophic level' which refers to the position occupied by an organism in the food chain.

Energy is passed on between trophic levels. Each time about 90% of the energy is lost

The products have more chemical energy than its reactants, as energy and heat is absorbed in the process.

There are 3 types of heat transfer; conduction, convection and radiation.

It is a well-known phenomenon now that substances expand on heating and contract on cooling. If you heat a body, it alters its dimensions. Depending on the shape of the body.

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The expansion can occur in length in which case it is called Linear Expansion.

If we take a square tile and heat it, the expansion will be on two fronts, length and breadth, here it is called Area Expansion.

Temperature is a measure of the average kinetic energy of the particles in an object. When temperature increases, the motion of these particles also increases. Temperature is usually measured in Kelvin or Celcius.

The energy absorbed breaks chemical bonds in the substance.

If we take a cube and heat it, all its sides expand and now the body experiences an increase in the overall volume due to this and it is called Volume Expansion.

General Flow Scenario: Autotrophs (solar energy fixed to energy in form of carbs via photosynthesis), Primary Consumers (gained energy is converted to body heat, energy to reproduce...), Secondary Consumers (energy obtained to grow, move, respire), Tertiary Consumers (feed on primary and secondary energy gained/ lost in process), Decomposers (break down the organic matter of the tertiary consumers and release the nutrients into the soil)

The energy given out forms bonds between atoms in the substance.

Thermal expansion can be defined as the change in the length, width, height, or volume of any material on changing the temperature.

Thermal expansion is best in solids as atoms are densely packed.

A reaction is deemed to be endothermic when the energy needed to from bonds is lesser than that needed to break them.

A reaction is deemed to be exothermic when the energy needed to from bonds exceeds that needed to break them.

Specific Heat Capacity

Specific heat capacity is defined as the amount of heat required to raise the temperature of 1 kilogram of a substance by 1 kelvin

It is used to indicate the ability of a substance to store heat.

The formula for calculating it is (Q= m x c x T)

A food chain is a series of nutrient and energy changes that moves through a chain of organisms. It always begins with a producer and terminates with decomposers

Examples:
producer → primary consumer → secondary consumer → decomposer (structure)
green plant → impala → leopard → bacteria

Trophic Levels: Producers - bottom of the pyramid, because they produce their food using photosynthesis
Primary Consumers - second level because they feed on plants (therefore maintain balance)
Secondary Consumers - feed on herbivores. there are fewer carnivores than herbivores. carnivores get their energy from plants indirectly and are on the third level.

Trophic Levels can be represented using: Pyramid of Numbers - total number of organisms
Pyramid of Biomass - total amount of biomass (living matter)
Pyramid of Energy - total amount of energy contents in the biomass

Represents the different feeding relationships in an ecosystem or a biome.

Made up using multiple food chains.

more complicated than a food chain because organisms can get their energy or food from more than one source.

if one organism is removed, the whole system will not collapse, unlike in a single food chain.

Convection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy.

Heat transfer by radiation occurs when microwaves, infrared radiation, visible light, or another form of electromagnetic radiation is emitted or absorbed.

Conduction occurs when energy is transferred from one atom or object to another. It takes place through either heat or electricity. Conduction can occur in liquid, gaseous or solid objects. For conduction to take place between two objects, they must be touching each other.