Classification(s):

1. States of Matter

   Liquids, Solids, Gases

2. Kinds of Materials

   Ceramics, Metals, Glass, Fibres, Plastics

7 types of Physical Properties:

1. Strength - refers to the ability of a material to withstand a heavy load without breaking or tearing.

2. Hardness - refers to the ability of a material to scratch another material.

   ★> A material can scratch something softer than itself, but not one that is harder than itself

3. Flexibility - refers to the ability of a material to bend without breaking and return to its original shape.*

4. Electrical Conductivity - a measure of how easily electricity passes through it.

5. Thermal conductivity - refers to how easily heat passes through it.

   ★> Materials that allow heat to pass through easily are thermal conductors

6. Melting Point - refers to the temperature at which a material changes state from solid to liquid.

7. Boiling Point - refers to the temperature at which a material changes state from liquid to gas.

Formula: Mass/Volume (SI: kg/m^3; kilograms per meter cube)

Definition: An element is a pure substance that cannot be broken down into any simpler substances by chemical methods.

Metals are good thermal and electrical conductors. Can be beaten up without breaking ahah so stronk.

Non-metals are poor thermal and electrical conductors and do not corrode unlike metals.

eg. Water (H2O) is made up of hydrogen (H) and oxygen (O2)

The different between mixtures and compounds is that mixtures are not joined together chemically unlike compunds.

Solutions are formed when one substance (solute) dissolves into another substance (solvent)

The solute is the substance that gets dissolved, whereas the solvent is the substance that dissolves the solute

Suspensions

Suspensions are formed when the solute does not dissolve but remains suspended inside the solvent. (eg. oil lying on the surface of water)

Filtering: Particle behaviour

When a solution (solute+solvent) is passing through filter paper, no residue gets left behind.

When a suspension passes through filter paper, a residue is left behind as the solid particles are too large to pass through the tiny pores of the filter paper

Definition: Solubility refers to the maximum amount of solute that can dissolve in a given amount of solvent (Factor 1) at a given temperature. (Factor 2)

When the maximum amount of solute gets dissolved, the solution becomes concentrated.

Rate of dissolving is a measure of how fast a substance dissolves in a solvent.

Two types of Cells:

Unicellular & Multicellular

Unicellular organisms function with ONLY ONE cell. (eg. Amoeba)

Multicellular organisms function with many cells. (eg. Humans)

Vacuole

- Small spaces containing air, liquid, or food particles

Cytoplasm

- Jelly-like substance that fills the cell

-Contains water and other substances

- Site of chemical reactions

Nucleus

- Controls activities within cell

-Contains chromosomes (made up of DNA)

Cell Membrane

- Thin layer around cell

-Partially permeable: allows some substances to pass through but not others

Mitochondria

- generate most of the chemical energy needed to power the cell's biochemical reactions.

Ribosome

- Site of protein synthesis

- Lies freely in the cytoplasm or attached to membrane bound organelle

Lysosome (out of syllabus)

- break down excess or worn-out cell parts

-destroy invading viruses and bacteria

Vacuole"

Cytoplasm"

Nucleus"

Cell Membrane"

Ribosome"

(") same as animal cell

Chloroplasts (unique to plant cells)

-Small disc-like structures found in the cells of green plants

-Contain chlorophyll, which absorbs energy from the sun and uses it for photosynthesis

Cell Wall

-Thick layer around cell

-Made up of cellulose

-Fully permeable

-Supports the cell and gives it a regular shape

No nucleus = carry more haemoglobin = more oxygen

Circular biconcave shape increasing surface area to volume ratio. This increases rate of diffusion of o2 in and out

they do not have cross walls to obstruct water flow through the lumen

their walls are thickened with lignin to prevent the vessel from collapsing

Tissue - Group of similar cells working together to perform a specific function

Organ - Different tissues working together to carry out a specific function

Organ system - Several related organs working together to carry out a particular function.

A physical change is a change in which no new substance is formed (eg. freezing water)

Physical changes can be reversed.

Energy in the form of heat may be taken in or given out during a physical change.

Chemical change/reaction

A chemical change is a change in which a new substance is formed.

They occur when matter interacts with heat, light, or electricity OR two or more different kinds of matter interact.

Energy in the form of heat, light, or sound etc. (or a combination of all) may be taken in or given out during a chemical change.

Chemical changes are represented by words and chemical equations.

Reactants undergo the change to form completely new substances (product) at the end of the reaction

Chemical changes are often irreversible.

One or more new substances may be produced.

Complete combustion occurs when there is a large supply of oxygen. This always produces carbon dioxide and water as the products.

this reaction is irreversible.

reaction involves oxygen, thus it is also filed under oxidation

Conditions for rusting

presence of oxygen (in air)

presence of water

Photosynthesis is a chemical change as carbon dioxide and water react in the presence of sunlight and chlorophyll to form glucose and oxygen

the total number of atoms in the product is the same as the total number of atoms in the reactants.

the total mass of reactants is the same as the total mass of the products in a single chemical reaction

this means that atoms in a chemical reaction are neither created nor destroyed.

For acids to react with alkalis, carbonates and metals, acids must be in aqueous state.

Physical properties

Sour taste

Acids turn litmus paper red

Acids turn green UI to red-yellow

Acidic solutions can conduct electricity

Alkalis

Physical properties

Bitter taste

Feels soapy when touched

Alkalis tur red litmus paper blue

Alkalis turn green UI to blue/violet

Acid + metal

Acid + carbonate

Acids react with reactive metals to produce salt and hydrogen gas. (This does not work with unreactive metals such as copper.)

Acids react with carbonates to form salt, water and carbon dioxide.

Acids react with alkalis to form salt and water. (Neutralisation)

Osmosis

Active transport

Diffusion can happen without a partially permeable membrane. However, sometimes membranes can stop diffusion from happening.

As it is a passive process, it does not require energy. Mineral salts move in and out the plant via diffusion.

Osmosis only involves water molecules.

It only occurs through a partially permeable membrane. This process only occurs when the particles are in liquid state, gaseous=diffusion.

The steeper the concentration gradient, the higher the rate of diffusion.

B) Size/mass of particle

The smaller/lighter the particle, the higher the rate of diffusion.

C) State

The more energy the particle has (at different states), the higher the rate of diffusion

D) Temperature

The higher the temperature of the particle, the higher the rate of diffusion.

However, in a solution of lower water potential, the cell will shrink in size and become crenated. In this case, cytoplasm has higher WP than the outside solution. Water leaves by osmosis.

In a solution of lower wp, the cell membrane pulls away from the cell wall and the cell becomes plasmolysed.

Cells that undergo active transport usually contain more mitochondria as the presence of more mitochondria can release more energy for active transport to occur.

Mineral salts to grow healthily

Water for photosynthesis.

This system consists of the roots, xylem tissue, and phloem tissue

Transports water and mineral salts from the roots to the leaves.

During photosynthesis, cells in the leaf have a higher concentration of o2 than the environment. Thus, o2 diffuses from the leaves to the environment. (opposite for co2, co2 diffuses from env into cells in leaf)

Diffusion also occurs at the roots. Dissolved mineral salts diffuse into root hair cells and then to the xylem.

Transpiration is defined as the loss of water, from the aerial parts of the plant, mainly through the stomata, in the form of water vapour

b) cooling. the evaporation of water removes latent heat from the plant

c) support. transpiration provides cells at all regions of the plant with water to remain turgid to keep the plant upright.

this is until the w and ms reach the stem

the circulatory system allows the quick transport of nutrients and oxygen to all body parts so that the body can release energy rapidly.

The arties carry blood away from the heart

The heart is a muscular pump. Its pumping action keeps the blood circulating around the body quickly and continuously.

oxygenated blood : heart to body

deoxygenated blood: heart to lungs

carries blood away from the heart

transports oxygenated blood from the heart to other parts of the body

capillary:

allows exchange of materials between blood and tissue

Capillary network increases surface area for faster exchange of substances between blood and cells

vein:

carries blood towards the heart

transports deoxygenated blood from body parts back to the heart

oxygen and nutrients move from blood in cap -> tissue fluid -> cells via diffusion

waste move from cells -> tissue fluid -> blood in cap -> excretory organs via diffusion

our body produces more red blood cells to transport more oxygen in areas with low oxygen

Blood consists of 4 components

Plasma (55% of blood)

RBC

WBC

Platelets

90% water

it dissolves food, waste products, hormones, proteins and antibodies and mineral salts

produced in the bone marrow, destroyed in the spleen

functions to transport oxygen to all respiring cells in the body

adaptive features:

contains haemoglobin to bind oxygen for transport

does not have a nucleus to allow more space for haemoglobin and thus more oxygen

biconcave shape to increase surface area to volume ratio for higher rate of diffusion

flexible to squeeze through blood capillaries

also bone marrow->spleen

produces lymphocytes (antibodies) and ingests phagocytes (foreign particles)

colourless and does not have haemoglobin

irregular shape

has a nucleus

can move and change shape (mobile) and squeeze through walls of thin capillaries

important for blood clotting