Introduction to Science Review

• The goal is to cover the Class 9 Science syllabus within 3-4 hours.

Matter - Definition

• It has mass and occupies space.

Matter - Physical Properties

• Atoms are the building blocks of matter.
• Matter consist of tiny particles.
• Particles have spaces between each other.
• Particles are continuously moving.
• Particles attract each other.

Matter - Potassium Permanganate Experiment

• Potassium permanganate crystals added to water turn it pink.
• Subsequent dilutions maintain a pink hue, demonstrating matter's minute particles.

Diffusion

• It involves substances mixing.
• The amount of a substance mixed with another.
• Temperature affects diffusion, with higher temperatures leading to increased kinetic energy and faster diffusion.
• Gases diffuse more rapidly than liquids, and liquids diffuse faster than solids.

States of Matter

Solid

• Atoms are tightly packed.
• Solids have a definite shape and volume.
• They are not compressible.
• Low kinetic energy exists in solids.

Liquid

• Atoms have space.
• Liquids have a fixed volume, but variable shape.
• Liquids are slightly compressible.
• They possess higher kinetic energy compared to solids.

Gas

• Atoms are widely spaced.
• Gases lack a fixed shape or volume.
• Gases are easily compressible.
• High kinetic energy characterizes gases.

Gases - Properties

• Significant space between particles.
• Particles have a weaker attraction.
• High kinetic energy is exhibited.
• There is no fixed shape or volume.
• Gases are easily compressed.

Temperature Conversion

Celsius to Kelvin

• Add 273 to Celsius for Kelvin conversion.

Kelvin to Celsius

• Subtract 273 from Kelvin for Celsius conversion.
• The SI unit for temperature is Kelvin.

Matter Transformation & Temperature/Pressure

Heating Solids

• Fusion is the conversion of solids to liquids.
• Vaporization is the conversion of liquids to gases.

Cooling Gases

• Condensation converts gases to liquids.
• Solidification converts liquids to solids.

Sublimation & Deposition

• Sublimation occurs when solids directly turn into gases.
• Deposition occurs when gases directly turn into solids.
• Example: Naphthalene balls disappearing illustrates sublimation.
• Pressure and temperature are inversely related in matter conversion.
• Increasing pressure turns gases to liquids and liquids to solids.

Dry Ice

• It's made by lowering the temperature and increasing the pressure of carbon dioxide.

Evaporation

• It is a surface phenomenon where liquid turns to vapor below boiling point.
• Evaporation leads to cooling.

Evaporation Factors

• Temperature: Higher temperatures increase evaporation.
• Wind Speed: More wind increases evaporation.
• Surface Area: Larger surface area increases evaporation.
• Humidity: Higher humidity reduces evaporation.

Relevance of Evaporation

• Wearing cotton clothes in summer aids sweat absorption & evaporation, cooling the body.
• Condensation causes water droplets on a cold glass.

Evaporation vs. Boiling

Evaporation

• It can happen at any temperature.
• A surface phenomenon on liquids.
• Causes cooling

Boiling

• It occurs at a specific temperature.
• Occurs throughout a liquid.
• Does not cause cooling.

Matter Around Us - Pure vs Impure

• Matter is either pure or impure.
• Pure substances are elements or compounds.
• Impure substances are mixtures.

Pure Substances Properties

• Inseparable atoms characterize pure substances.
• They exhibit uniform chemical properties.
• They have a defined composition.

Elements

• Elements are basic matter forms that cannot be broken down.
• They are categorized as Metals, Non-metals, or Metalloids (mixed properties).

Elements - Metals

• Metals are lustrous.
• Conduct electricity and heat.
• Metals are malleable, ductile, and sonorous.

Elements - Non-Metals

• Non-metals lack luster.
• They do not conduct electricity or heat.
• Non-metals cannot be hammered into sheets.

Elements - Metalloids

• Metalloids have properties between metals and nonmetals.
• Boron and Germanium are examples of metalloids.

Compounds

• Substances of two or more elements in a fixed ratio.
• Elements combine in a set ratio.
• Properties are different from constituent elements.
• They're separated only by chemical methods.
• Ratio: Hydrogen & oxygen combine at 1:8 to form water.

Mixtures

• Mixtures have substances mixed in any ratio.
• Mixtures can be separated physically.
• Mixtures include different elements.
• Can vary ingredients
• Mixtures are either Homogenous or Heterogeneous.

Mixtures - Homogenous

• Uniformly mixed components, the ingredients that can't be seen
• They cannot be separated only by physical means.
• Example: Sugar and water is a homogenous mixture.

Mixtures - Heterogenous

• Non-uniformly mixed components, the ingredients can be seen
• They can be separated by physical means.
• Example: Soil and water is a heterogeneous mixture.

True Solutions, Colloidal & Suspensions

True Solutions

• Particles are small.
• Filtration doesn't separate them.
• Translucent
• Light is not scattered.

Colloidal Solutions

• Particles are slightly large.
• Filtration cannot separate them.
• Transparent
• Light scatters.

Suspensions

• Particles are large.
• They can be separated through filtration.
• Opaque
• Light scatters.

Solutions

• Homogenous
• Consist of a solute (lesser quantity) & solvent (larger quantity).
• Concentration is the amount of solute in a solvent.
• Concentration = (Mass of solute / Mass of solution) x 100.

Solubility

• The max solute amount dissolved at a given temperature.

Temperature & Solubility

• Higher temperature equals increased solubility.
• Saturated solutions have reached maximum solubility.
• Saturated solution is when the solution has reached max amount of solute.

Colloidal Solutions: Two Parts

Dispersed Medium

• Acts like the solvent.

Dispersed Phase

• Its role is that of the solute.

Emulsion

• It is a mixture of two liquids.
• Milk is an example of emulsion.

Suspensions

• They're heterogeneous mixes of larger particles.
• Tyndall effect occurs.

Physical vs Chemical Change

Physical Change

• No new substances are created.
• Physical change involves change in state, size, or shape.

Chemical Change

• New substances are created.
• Properties are altered.
• It it's irreverisble, a new aubstance form

Atoms and Molecules - Atomic Theory

• Democritus introduced Atoms.
• Antoine Lavoisier discovered Conserved Mass.
• John Dalton also studied Atoms.
• All matter consists of indivisible particles.
• All have identical mass properties.

Limitations of Dalton's atomic theory

• Subatomic particles could be proven.
• Isotopes were not defined.

Modern Day Symbols of Elements

• The first letter of the element is used as its symbol.
• Exceptions exist due to language differences.

Atomic Mass

Rule of Thumb

• if the Atomic # is even then * 2
• If the Atomic # is odd * 2 + 1

Exceptions to atomic mass

• Hydrogen
• Chlorine
• Argon
• Nitrogen

Atomic number Defined

• Comparing based of 1 mass to 12 carbon or 1 mass unit.

Atom Relationships

• Atoms relate by building bonds.
• Atoms that mix are called Molecules.
• Inert gasses like helium do not create molecules.

Ions

• Atoms with a +/- charge.
• Cations are positively charged.
• Anions have negative charges.
• Metal = positive, nonmetal = negative, with a positive charge to most.
• Polyatomics exist, and must be learned.

Molecules

• Molecules of elements like O2 mix only from that element.
• Molecules of compounds have 2+ different elements.

Atomicity

• of elements is defined molecule; HO2 = 1/3.

Molecule Mass

• The total is all in the atoms.

Formula Unit

• The mass, based on an ionic compound.

Valency

• An element's combining capacity
• Same as oxidation state.

Writing Formulas

• Write the ion and cross.
• Example Aluminum / oxide Al^+3 O=2.

Structure of an Atom - J.J. Thomson

• Cathode Ray was used to discover electrons in 1891.
• Charge is 1.6x10^19.
• Mass 31kg

Eugen Goldstein

• Did a new experiment on Protons
• 2000 mass

James Chadwick 1932

• Discovered Neutrons / No Charge/ Mass.
• Mass # is protons + Neutrons.

Thomson Model

• Plum pudding model with equal parts negative and Positive.
• Positive sphere e- embedded.

Thomson Model Limitations

• Rutherford's model showed it was not the case

Rutherford Model

• e- a +2
• Most went straight; some bounced or were deflected.
• Most of the atom is empty space.
• Nucleus has positive charge and contains mass.
• Nucleus less 1.

Bohr Model

• Bohr said that If Revolving Loses Energy Nucleos
• e- doesn't lose energy.
• Each orbit is specific.
• Energy is lost - orbit switch.
• Gain goes large, loss goes lower.

Atomic Number

• Atomic # is = to the protons.
• Elements are electrically neutral, so electrons = protons.

Electron Distribution

• Follow the 2N^2 rule.

Shell Rules

• Fill shells in order
• Valency less 5-8.

Iso + Bar

• Tops = isobars
• Isobars have the same mass #.

Cell Division

• The fundamental unit, each divided with different properties and functions.

2 Types of Cell Division for Growth & Reproduction

Mitosis vs. Meiosis

• Mitosis a cell has 2 daughter cells, meiosis has 4.
• Chromosome
• Reproduction

Tissue

• Many cells unite for 1 job.

Tissue In Plants

• Meristematic (divides)
• Permanent (does not divide)

Meristematic: 3 Types

• All types are in a stem.
• Apical is positioned on tips and shoots.
• Lateral
• Intercalary.

Tissue - Permanent

• Simple: simple group of PCO's.
• Complex: 2 kinds: Xylem & Phloem.

Simple Permanent P

• Parenchyma (PA): supports, and stores. It's living and thin, with space in cells.
• Collenchyma (CO): Like PA but with less shape flexibility.
• Sclerenchyma (Scl): Lignin cell wall like coconut. Dead.
• Chlor and aero are PA = 9 and 8.

Tissue - Complex

• Xylem (Xy): Transports water, 1 direct dead and living.
• Phloem (Flo): Transports food, bi-direct, 3 alive, 1 dead.

Tissue - Animal: 4 Types

• Epithelial: 1 layer skin.
• Squamous: Lining of the mouth.
• Striated
• Columnar: Intestines.
• Cuboidal: Kidneys.

Muscle: 3 Types

• Striated muscles are voluntary, like the muscle.
• Non-striated muscles are NOT voluntary, like the digestive stomach.

Connecting Tissue

• Tendons connect muscle and bone.
• Ligaments connect bone to bone.

Bone vs. Cartilage

• Bone is hard.
• Cartilage is soft.
• Bone has blood.
• Cartilage has no blood.

Human Nervous System

• Dendrite for signal reception.
• Soma is the cell body.
• Axon

Motion

• The body is changing/not changing with time.
• Scale = time.

Velocity

• Displacement/shorter time

Velocity Speed

• Change = acceleration, Distance^2 /Time

Review of matter for Class 9 Science. Covers the definition of matter, physical properties, potassium permanganate experiment, and diffusion. Explains how temperature affects diffusion rates in gases, liquids and solids.