PHYSICAL SCIENCE

Module 6: Chemical Reactions

  • Laws of Conservation of Energy

    • Atoms can neither be created nor destroyed in a given chemical reaction

    • The number of atoms that are in the reactants has to balance the number of atoms in the products.

  • Proust’s Law of Definite Proportions

    • The elements are in a fixed ratio

    • Elements in a compound are always in the same mass ratio—if the ratio changes, it is an entirely different compound.

Chemical reaction

  • Chemicals interact to form new chemicals with different compositions

  • Reactants - Starting materials (either elements or compounds)

  • Products - Result of the chemical reaction and have different chemical properties from the reactants

  • Chemical change - breaking old and making new chemical bonds to rearrange atoms from the reactants

Types of Chemical Reactions

  1. Synthesis Reaction (Combination reaction)

    • Two or more simple substances combine to form a more complex product

    • A + B → AB

  2. Decomposition Reaction

    • Opposite of synthesis reaction

    • The breakdown of a single complex compound to simpler compounds/elements

    • AB → A + B

  3. Single Replacement Reaction

    • One element replaces another element in a compound

    • A + BC → AC + B

  4. Double Replacement Reaction

    • Compounds undergo exchange of their elements with each other

    • AB + CD → AD + CB

  5. Combustion Reaction

    • A rapid chemical reaction between a fuel and an oxidant (usually O) that releases heat and light

Stoichiometry

  • Stoikhein (element) and metron (measure) = measure of elements

  • Given gram x 1 mol/molar mass (gram) of element a = moles a x moles B/moles A (mole ratio) = moles b x molar mass (grams) of element b/1 mol = grams of element b

  • Mole

    • The amount of substance containing the same number of discrete entities like atom or molecules

    • Number of molecules can be calculated with moles using Avogadro’s number (6.022 × 1023)

      • Represents the number of molecules in one gram of a compound (or element)

    • Mole ratio

      • Ratio between any two substances in a balanced reaction

    • Molar mass

      • Mass of one mole of a substance

      • g/mol or kg/mol

Gases in Stoichiometry

  • 1 mole of gas = 22.4 L

Limiting reactant

  • Consumed first in a chemical reaction among other reactants

  • Limits the amount of products that can be formed

Excess reactant

  • Not fully or entirely consumed/reacted in a chemical reaction

  • Does not limit the amount of products that can be formed

Module 7: Models of the Universe and the Early Astronomy

  • Orlando Ferguson’s Map of the Square and Stationary Earth

  • Pythagoras - First to originate a spherical earth by north-south constellations, sinking ships and lunar eclipse

  • Plato - Earth forms a globe and is equidistant from the center: it is the center of the universe, perfect and eternal, has four elements (WAFE)

  • Aristotle - Idea of geocentric universe with fixed spherical earth as center

    • Rounded shadow of the earth in the moon

    • Change in constellations

    • Indirect idea on gravity

  • Eratosthenes - gave the most accurate size (non-scientific calculation)

Figures for guidance:

Geocentric theorists

  • Plato

  • Aristotle

  • Ptolemy

  • Tycho Brahe

Heliocentric theorist

  • Aristarchus of Samos

  • Nicolaus Copernicus

  • Galileo Galilei

  • Johannes Kepler

Ancient Astronomy

  • Plato - Universe is perfect and unchanging. Questionned the circular paths of planets

  • Eudoxus of Cnidus - There are 27 interconnected geocentric spheres

  • Aristotle - Added 3 spheres to jupiter and mars and 4 sphere to sun, moon, venus and mercury (3 JM, 4 SMOMEV)

  • Claudius Ptolemy - Earth is spherical, stars are fixed, planets move independently and planet can reverse their motion.

  • Aristarchus of Samos - Sun and stars are fixed and estimated the size of sun and moon through earth’s size and estimated the distance of earth to the sun and moon

Modern astronomy

  1. Observations became more quantitative

  2. Theories based on logical and mathematical concepts

  • Nicolaus copernicus - Proposed the heliocentric theory, tilting of the earth, and the four seasons

    • Earth as only one of the planets

    • Earth rotates in axis daily and around the sun once a year

    • Annual tilting of axis

    • Retrogade motion explained by earth’s motion

    • Distance of earth to sun is smaller than earth to stars

  • Tycho Brahe

    • Modified the geocentric model

    • Made instruments for precise measurements for positions of planets

    • Discovered supernova in constellation cassiopeia

    • Tychonic system

  • Galileo Galilei

    • Used the telescope to observe

    • Discovered sunspots and rough surface of the moon

    • Discovered the 4 famous moons of jupiter

    • Venus has phases like moon

  • Johannes Kepler

    • First law- Orbits as ellipses and sun at focus

    • Second law - Imaginary line between sun to a planet where it is in equal areas in equal time. Periphelion near to sun and Aphelion far to sun

    • Third Law - Cube of radius of the planet’s orbit is proportional to the square of its period of revolution

Module 8: Kinematics and Theories about Motion

  • Aristotle’s Theory of Motion

    • Object are made of 4 primordial elements (WAFE)

    • 2 types of motion: Natural and Violent

      • Natural motion - motion naturally without forcing motion to happen

        • 1st theory - Object made of earth falls toward the center of the Earth to seek it natural place

        • 2nd theory - Heavy object fall faster than lighter ones

        • 3rd theory - objects fall faster in air than water

        • 4th theory - objects sometimes move away from natural places

      • Violent motion - a motion requires a force to make an object move in unnatural manner

    • Longevity of aristotle’s theory of motion: it was consistent in common sense, no other theories were made that time, quantitative method was not yet developed

  • Galileo Galilei’s Finding about Motion

    • First finding - 2 objects (light and heavy) fell and struck the earth at the same time **Acceleration due to gravity

    • Second finding - A marble on a flat surface will infinitely roll **Law of inertia

    • Third finding - When a marble is rolled in an inclined plane at a fixed angle, the distance covered and the square of time was constant **velocity (d/t)

    • Fourth finding - On a free falling object, gravity causes object to be uniformly accelerated **UAM Uniformly Accelerated Motion

Free fall motion

  • Type of motion under the sole influence of gravity

  • Vi is 0

Vertical Upward Motion

  • Type of motion that follows a vertical upward path resisting the effect of acceleration due to gravity

  • Vf is 0

Projectile Motion

  • Type of motion along two dimensions acted upon by gravity. Combines the constant velocity (x) and constant acceleration (y)

  • Object is called projectile and the path is the trajectory

  • Motion of object vertically upward into the air moving dependently on gravity and horizontally independently of gravity. Vertical = dependent on gravity, Horizontally = independent on gravity

MODULE 9: Newton’s Laws of Motions

  • The earth is attracted to apple and apple is attracted to earth → laws of universal gravitation and laws of motion

  • Gravitational theory - observing an apple fall to the ground

First Law: Law of Inertia

  • An object at rest remains at rest; an object in motion remains in motion → it changes when it is acted on by an unbalanced force

    Force - a push or pull motion that changes an object’s state of motion

    Balanced Force -

Parts of a chemical equationState conditionStoichiometry formulaConverting using avogadro's numberThird law of Johannes KeplerKinematics formulaVertical upward motion