science semester 2 yr 9

chemical reactions and ecosystems

Ecosystem

All living + nonliving things interacting in an area.

Community

All different species living together.

Population

Members of one species living in the same area.

Carrying Capacity

Maximum population the environment can support.

Abiotic Factors

Nonliving: temperature, water, soil, sunlight.

Biotic Factors

Living: predators, competition, disease, food availability.

Introduced Species

Non-native; can become pests, reduce biodiversity

Human Impacts

Pollution, land clearing, overfishing, climate change.

Natural Disasters

Bushfires, floods, droughts → rapid population change.

Predator–Prey

One hunts; one is eaten.

Competition

Organisms fight for the same resource.

Mutualism

Both benefit (+/+).

Commensalism

One benefits, other unaffected (+/0).

Parasitism

Parasite benefits, host harmed (+/−).

Inhibition

One organism prevents growth of another (e.g., plants releasing chemicals).

Producer (Autotroph)

Makes own food (plants)

Consumer (Heterotroph)

Eats others for energy

1st-order consumer is a

herbivore

2nd-order consumer is a

eats herbivores

3rd-order consumer is a

top carnivore

Food Chain

One path of energy

Food Web

Many linked food chains.

Carrying Capacity

Energy limits how many organisms can survive.

Carbon Cycle

Carbon moves through atmosphere, organisms, oceans, soil.

Photosynthesis chemical equasion

CO₂ + H₂O → glucose + O₂

where does photosynthysis happen

Occurs in chloroplasts (chlorophyll)

Stomata

Leaf pores where gases pass.

where does Cellular Respiration happen

Occurs in mitochondria.

chem equasion for cellular respiration

Glucose + O₂ → CO₂ + H₂O + energy

Decomposers

Break down dead matter → recycle nutrients.

Greenhouse Gases

CO₂, methane, water vapour → trap heat.

Enhanced Greenhouse Effect

Extra warming caused by human activity.

Atom Structure

Protons (+), neutrons (0), electrons (−).

Electron Configuration

Example: 2,8,8.

Ion

Charged atom.

Cation

Positive ion (lost electrons).

Anion

Negative ion (gained electrons).

Element

Pure substance made of one atom type.

Compound

Two+ elements chemically joined.

Mixture

Substances not chemically joined.

Word Equation example

E.g., hydrogen + oxygen → water.

Balanced Equation

Atoms on both sides equal.

Coefficient

Big number in front of formula.

Subscript

Small number in formula after element (e.g., O₂)

Law of Conservation of Mass

Mass of reactants = mass of products.

Reactants

Starting chemicals.

Products

New chemicals formed.

Exothermic

Releases heat (hot)

Endothermic

Absorbs heat (cold).

Combustion

a reaction where a fuel reacts rapidly with oxygen to produce heat, light, and an oxide compound

Acids

pH < 7 (sour).

Bases

pH > 7 (bitter, slippery).

Neutralisation

Acid + base → salt + water.

Energy Profile Diagram

Shows energy change during reaction.

Factors Increasing Rate:

• Higher temperature
• Higher concentration
• Larger surface area
• Catalyst added

Steeper line 

faster reaction

Plateau

reaction finished.