Physical Science Past Paper PDF (2019)

‎ HYSICAL SCIENCE P Atom ‎ It is a branch of natural science ‎ the smallest unit of matter that have all the that studies non-living systems, in properties of an element. They composed of contrast to life science...

‎ HYSICAL SCIENCE P Atom ‎ It is a branch of natural science ‎ the smallest unit of matter that have all the that studies non-living systems, in properties of an element. They composed of contrast to life science. It in turn smaller subatomic particles as protons, has many branches, each referred neutrons, and electrons. to as a "physical science", together called the "physical ‎ tomic Number (Z) A sciences". ‎ indicates the number of protons in an atom. In a neutral atom, number of protons is equal ‎ osmology C to the number of protons is equal to the ‎ is a branch of astronomy that number of electrons. involves the origin and evolution of the universe, from the Big Bang ‎ tomic Number (A) A to today and on into the future. ‎ equal to the sum of the number of protons and neutrons. ‎ Cosmic Stages 3 ‎1. Big bang nucleosynthesis I‎ sotope formed the light elements (H, He, ‎ refer to atoms with the same atomic number and Li). but different atomic masses. ‎2. Stellar formation and evolution formed the elements heavier than ‎ umber of Neutrons = Atomic Mass - N Be to Fe. Atomic Number ‎3. Stellar explosion, or supernova, formed the elements heavier than Fe. I‎ ons ‎ which are positively or negatively charged ‎ ig Bang Theory B particles, have the same number of protons in ‎ explains how the elements were different number of electrons. initially formed the formation of different elements involved many nuclear reactions, including fusion, fission and radioactive decay ‎ part of its proof is the amounts of H and He we have in the universe today. ‎Stage of Big Bang Theory ‎ Singularity a point in space and/or a moment in time where the universe was infinitely hot and dense. I‎ nflation ‎ theory of exponential expansion of space in the early universe. The inflationary epoch lasted from 10-36 seconds. ‎Nucleosynthesis ‎ the process that creates new atomic nuclei from pre- existing nucleons, primarily protons and neutrons. ‎ as the Universe cools, protons and neutrons can fuse to form heavier atomic nuclei ‎Recombination ‎ refers to the epoch at which charged electrons and protons first became bound to form electrically neutral hydrogen atoms. ‎ nnihilation A ‎ in physics, reaction in which a particle and its antiparticle collide and disappear, releasing energy. ‎ edshift R ‎ the displacement of spectral lines toward longer wavelengths (the red end of the spectrum) in radiation from distant galaxies and celestial objects. ‎ osmic Microwave Background (CMB) C ‎ electromagnetic radiation left over from an early stage of the universe in Big Bang cosmology.  STARS Stelllar Evolution → is the process by which a star changes over the course of time. → Scientists believe that the formation of the universe began through the explosion of a primordial atom which happened approximately 13.7 billion years ago. The origin of the universe is described by the Big Bang theory which was introduced by Edwin Hubble. In 1929, Hubble demonstrated that all celestial objects in the universe move away from each other Stellar Nucleosynthesis → is the process by which the natural abundances of the chemical elements within stars vary due to nuclear fusion reactions in the cores and overlying mantles of stars. Supernova Nucleosynthesis → is a theory of the production of many different chemical elements in supernova explosions, first advanced by Fred Hoyle in 1954. Main Sequence Star → is any star that is fusing hydrogen in its core and has a stable balance of outward pressure from core nuclear fusion and gravitational forces pushing inward. Red Giant Star → is a dying star in the last stages of stellar evolution. Supernova → the largest explosion that takes place in space. Proton Proton Chain Reaction → is one of the two (known) sets of fusion reactions by which stars convert hydrogen to helium. It dominates in stars the size of the Sun or smaller. Triple Alpha Process Nucleosynthesis → is a set of nuclear fusion reactions by which three helium-4 nuclei (alpha particles) are transformed into carbon. Alpha Ladder/Process → is one of two classes of nuclear fusion reactions by which stars convert helium into heavier elements, the other being the triple-alpha process. → In Astrophysics, alpha ladder is the sequence of reactions that form alpha elements starting from Silicon-28. After Silicon, elements with mass numbers as multiples of 4 are formed, Ar, Ca, Ti, Cr, Fe and finally Ni-56. Only massive stars have the potential to form Ni-56. Our Sun doesn't have enough mass and stops at C CNO Cycle →It is a catalytic cycle. → (for carbon-nitrogen-oxygen) is one of the two known sets of fusion reactions by which stars convert hydrogen to helium. R-Process → involves rapid capture of neutrons by the atom. S-process / Slow neutron Capture Process → involving slow neutron capture in red giants. ATOMIC STRUCTURE ( ATOMIC MODELS AND THEORY ) Level of Organization in an Organism Atom - Molecule - Cell - Tissue - Organ - Organ system - Organism ARISTOTLE Proposed that all substances are composed of four elements such as air, earth, fire and water in different proportion. DEMOCRITUS Together with Leucippus proposed that everything is composed of very small bit of matter that is indivisible and called it atom. JOHN DALTON Came up with the so-called atomic theory after he gathered all the findings and results of various experiments made by the ancient philosophers. WILHELM ROENTGEN Discovered X-ray by observing the fluorescence they produced. JOHN DALTON'S ATOMIC THEORY 1. All matter is composed of extremely small, indivisble, indestructible particles called atoms. 2. All atoms of each element are exactly alike but they differ from atoms of other elements. The atoms of different elements have different mass and other properties. 3. When atoms of different elements combine to form a compound, the constituent atoms are always present in the same fixed numerical ratio. 4. A chemical reaction involves a rearrangement of atoms. No atom is created or destroyed. JOSEPH JOHN THOMSON discovered the electron. NEIL BOHR Proposed the planetary model of an atom. JAMES CHADWICK He discovered the neutron. ATOMIC STRUCTURE ( THE FUNDAMENTAL COMPONENTS OF THE ATOM ) THE SUB-ATOMIC PARTICLES Proton p+ positive Electron e- negative Neutron n⁰ no charge CATION An atom that loses an electron becomes positively charged ion called cation. ANION The one that gains electron becomes negatively charged ion called anion. ATOMIC NUMBER Its symbol is Z. It represents the number of electrons as well as protons. The "numeric identity" of the element.  MASS NUMBER The sum of the numbers of protons and neutrons. Its symbol is A. FOR A NEUTRAL ATOM Number of protons = Number of electrons = Atomic Number (Z) Mass number (A) = Number of protons + Number of neutrons Number of neutron = Atomic number (Z) - Mass number (A) ATOMIC STRUCTURE ( THE QUANTUM MECHANICAL MODEL OF AN ATOM ) ELECTRON There is a definite order to the arrangement of electron in atoms. The lowest energy level or energy state is called the ground state. Atoms with complete valence electron tend to be stable, closed shell. MAXIMUM NUMBER OF ELECTRON IN AN ENERGY LEVEL ENERGY LEVEL, N MAXIMUM NUMBER OF ELECTRONS, 2N² 1 2 2 8 3 18 4 32 ATOMIC ORBITALS s orbital sharp 2 p orbital principal 6 d orbital diffused 10 f orbital fundamental 14 ELECTRON CONFIGURATION The probable distribution of electrons around the nucleus among the orbitals. Shorthand representation on how each electron is arranged among the orbitals, levels, and sub-levels. The electron configuration is represented by a number, a letter and a superscript. The number corresponds to the principal quantum number n, the letter can be any of the different sub-levels (s, p, d or f) and the superscript represents the number of electrons occupying an assigned orbital. THREE RULES SERVES AS GUIDES TO EASILY PREDICT ELECTRON'S LOCATIONS: The Pauli's Exclusion Principle states that no more than two electrons in an atom can occupy an orbital. They must spin in opposite direction. Electrons are said to be paired if two electrons with opposite spins occupy an orbital and unpaired if a single electron is present in the orbital. The Hund's Rule (Principle of minimum pairing and the principle of maximum multiplicity) proposed by Friedrich Hund, states that for a set of orbital contains one electron with parallel spins. The Aufbau Principle (German word: "building up or construction") states that electron fill first the orbitals of the lowest energy (ground state) until added electrons occupy the available orbital of higher energy (excited state)  HOLDS ATOMS TOGETHER FORMATION OF COVALENT COMPOUNDS IONIC BOND When two or more non-metallic COVALENT BOND elements combine in a covalent METALLIC BOND bonding, a molecule is formed. DMITRI MENDELEEV The gases like O2, H2, N2, F2, Cl2, The one who created the periodic table Br2, and I2, diatomic molecule. Groups And Periods TYPES OF COVALENT BOND Periods going horizontally. Single Covalent Bond Groups (family) going vertically. Denoted by one short line (---), is the Octet Rule Stability sharing of one electron pair between Refers to the strength to stand two atoms. or a resistance to chemical A Double Covalent Bond change or to physical Denoted by two short lines (=), is the disintegration. sharing of two electron pairs. It involves the possession of eight Triple Covalent Bond electrons in its outermost energy Denoted by three short lines, is the level or valence electron. sharing of three electron pairs. Lewis Electron Dot Structure (LEDS) Naming Covalent Compounds It is a shorthand method which (1) You have to name first the first non consists of a symbol of the metal. element surrounded by dots. (2) The second non-metal is named by The symbol represents the changing ist suffix with-ide. nucleus of the atom while the (3) A prefix such as mono, di, tri, etc. dots represent the valence is used in front of each element to electrons of the atom denote the number of atoms present in How to draw the LEDS? the element. Step 1: Write the chemical symbol of an atom. Metallic Bond Step 2: To find an atom's valence electrons, Third type of chemical bonding, this identify its column in the periodic table or type of bond is a bond among metals. write its electron configuration. For The electrostatic force that holds the representative elements, valence electrons atoms together in metals is called equal the group number. metallic bond. Step 3: Draw dots representing the atom's Metallic Elements valence electrons, distributing them evenly Located at the right side of the around the chemical symbol. periodic table. Metals are malleable Ionic Bond and ductile and have high melting transfer of electrons from one atom to another. point. They are good conductor of Compounds heat and electricity. Elements react with one another forming new Why are metals good conductor of heat? substances. Materials bonded by metallic bonds are good The compounds are bind together by a strong electrical and thermal conductors due to their attractive force called chemical bond. free valence electrons. Covalent Bond Why do metals have high boiling point? Elements involve in covalent bond do not The high melting points of transition elements in transfer electrons but instead they share the d-block, such as Fe, Ru, and Os, result from electrons. the electrostatic attraction between metal This type of bonds exists between non- cations and the surrounding valence electron metals. fluid. Why are metals malleable and ductile? Malleability is the ability to be shaped by pressure, either by hammering, rolling into sheets, or forging. Ductility is the ability of metals to be drawn into a wire. These two properties are derived from the non-directional nature of the attractions between the atoms. Why are metals shiny? Luster is the ability to shine. It is the ability to reflect light. The presence of free electrons that vibrate and move are the reasons why metals reflect light. BIOMOLECULES CARBOHYDRATES Biomolecules are polymers (Greek polus meaning Comes from the french term hydrate de carbone which "many") of repeating units of smaller molecules called means "hydrates of carbon". It is something called monomers (Greek monos means "single"). sacchride from the Greek word sakcharon meaning Biomolecules are organic molecules produced by "sugar". While, the suffix -ose is used to denote the living organisms which consist mainly of elements name of saccharide. Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N). Most abundant class of biomolecules Non-metal which combines in various ways to form Chief source of energy of almost all living organisms. the boimolecules through a covalent type of bonding. Without them life would not exist. Examples are Fruits, Sweets, Bread, Pastas, Potatoes, Two Forms of Biomolecules Beans and Cereals. Large molecules are knows as Macromolecules. (E.g. Polysaccharides, Nucleic acids, Proteins, and Lypids) Sugar, Starch, and Cellulose are groups of carbohydrates and are all made up of the elements Small molecules are known as Micromolecules. (E.g. Carbon, Hydrogen, and Oxygen. Simple sugar, Nucleotides, Amino acids, and Fatty acids / Glycerol) The production of these Carbohydrates by green Elements present in Biomolecules plants is possible through the process of Carbon (C) photosynthesis. Nitrogen (N) Types of Carbohydrates Hydrogen (H) Carbohydrates may be group into two: the Oxygen (O) micromolecule (monosaccharide) and the Phosphorus (P) macromolecule (disaccharide & polysaccharide) Sulfur (S) Monosaccharide - single sugar molecule Disaccharide - two sugar molecules linked 4 different classes of Biomolecules Polysaccharide - many sugar molecules linked 1. Carbohydrates (C, H, O) 2. Lipids (C, H, O) PROTEINS 3. Proteins (C, H, O, N, S) Complex biomolecules that contains amino acid 4. Nucleic Acid (C, H, N, O, P) (building blocks of protein) linked through the FOOD LABEL peptide bonds. The most versatile biomolecule since they serve - Gives you the list of nutrition information, such as fat numerous essential functions in the biological and protein content, the ingredient and some additive. processes. - Required on most packaged food to help inform the Due to nitrogen component it separate proteins from public or customers in making food choices. carbohydrates. Why reading food labels is important? Protein Structure a) Helps poeple make food choice 1. Primary structure - the linear sequence of amino acids b) Helps people with food allergies that form a protein. c) It informs you if it contains additives that must avoid 2. Secondary structure - the spatial arrangement of the d) To help control weight and improve health polypeptide chain of a protein. 3. Teetiary structure - refers to the final three- CALORIE and PDV dimentional shape of a single polypeptide molecule Calorie is the measument of how much energy food where the alpha helix and the pleated sheet are provides. folding forming a globular protein. 4. Quarternary structure - contains more than one chain. PDV (Percent Daily Value) shows the amount of Refers to the overall shape when two or more nutrients an average person is required from eating one polypeptides bind each other. "Hemoglobin" serving of that food. NUCLEIC ACIDS First isolated from the nuclei of white blood cells by Friendrich Miescher in 1860s. It is responsible in encoding, transmitting and expressing genetic information. NUCLEOTIDES One phosphorus with four (4) oxygen (a phosphate group); A five-carbon sugar (deoxyribose) A nitrogen-containing base (either a single ringed pyrymidine or a double-ring purine). NUCLEIC ACIDS: RNA & DNA DNA (Deoxyribonucleic Acid) - generally double-stranded RNA (Ribonucleic Acid) - generally single-stranded CHARGAFF'S RULE OF DNA In 1950s by Edwin Chargaff A = T (Adenine pair with Thymine) G = C (Guanine pair with Cytocine) LIPIDS Large and diverse group of naturally occurring biomolecules that can be dissolved away from biological materials by solvents that are nonpolar like ether, acetone, and benzene. Lypids are hydrophobic which means they are insoluble in water. Glycerol and Fatty acids are the building blocks of lipids. Formed when fats and oil are heated with aqueous solution of bases. Saponification "soap making". Primarily involved in the formation of cell membrane, which is a bilipid layer. TYPES OF LIPIDS Triglycerides (H & C) Plants and Animals Steroids - one of the most plentiful lipid in our body. PROTON-PROTON CHAIN REACTION It begins with a proton and a neutron fusing together to create deuterium. When another proton collides with deuterium, helium-3 is produced. A collision between two helium-3 atoms leads to the formation of helium-4. CNO (CARBON, NITROGEN, OXYGEN) CYCLE Carbon-12 fused with proton (H) and form Nitrogen-13. Nitrogen-13 undergoes beta decay to form Carbon-13. Carbon-13 captures proton (H) and Nitrogen-14 is formed. Nitrogen-14 captures proton to produce Oxygen-15, and Oxygen-15 undergoes beta decay that forms Nitrogen-15. The Nitrogen-15 fused with proton gives off Helium to generate the stable atom of Carbon-12. TRI ALPHA PROCESS happens in red giant star once they leave the stage of main sequence star. This is how three Helium-4 are converted into Carbon. ALPHA LADDER PROCESS A star accumulates more mass and continues to grow into red super giant. Alpha particle fusion happens at its core and creates more heavy elements until Iron. NEUTRON CAPTURE CAN BE SLOW OR RAPID; S-process or slow process happens when there is a slow rate of capturing neutron while there is a faster rate of radioactive decay hence increasing the proton by The R-process (rapid process) captures neutrons quickly before radioactive decay, allowing for the formation of heavier elements than iron during supernova nucleosynthesis. HOW DO ELEMENTS HEAVIER THAN IRON FORM? As the energy at the core of the star decreases, nuclear fusion cannot produce elements higher than Iron. A different pathway is needed for heavier elements to be formed. POLARITY OF MOLECULES: (FORCES OF ATTRACTION IN MATERIALS) WHAT IS POLARITY? Polarity in a molecules determines whether or not electrons in that molecule are shared equally. When determining the polarity of a molecule, it is all about symmetry. Asymmetric molecules tend to be polar. Symmetric molecules are always non-polar STEPS IN DETERMINING THE POLARITY OF MOLECULE: Draw the Electron Dot structure of the molecule. Using the electronegativity chart determine the difference in electronegativity for each bond. 0-0.4 Non-polar 0.5-1.9= Polar POLARITY OF MOLECULES A molecule is polar if it contains polar bonds AND There are unshared electrons on a central atom OR The bonds from the central atom involve different atoms A molecule is nonpolar if It contains only nonpolar bonds OR All the bonds to the central atom are the same and there are no unshared pairs on the central atom So, a nonpolar molecule may contain polar bonds because the dipole moments of the individual bonds cancel out, DIPOLE MOMENTS Dipole Moments (µ) a quantitative measure of the polarity of a bond. µ = charge x distance = Qxr (distance is in meters) Dipole moment units are the Debye Bond dipole moment is a vector quantity - it has a magnitude and direction. Molecular dipole moment = vector sum of all bond moments Direction of the polar bond in a molecule. Arrow points toward the more e neg atom. NONPOLAR MOLECULES Dipole moments are symmetrical and cancel out. POLAR MOLECULES Dipole moments are asymmetrical and don't cancel. Molecule has a net dipole moment. The effect of polar bonds on the polarity of the entire molecule depends on the molecule shape water has two polar bonds and a bent shape; the highly electronegative oxygen pulls the e away from H = very polar! POLAR BONDS VS. POLAR MOLECULES The effect of polar bonds on the polarity of the entire molecule depends on the molecule shape carbon dioxide has two polar bonds, and is linear = nonpolar molecule! DETERMINING MOLECULAR POLARITY Therefore, polar molecules have... asymmetrical shape (lone pairs) or asymmetrical atoms WHAT IS EN OR ELECTRONEGATIVITY? Electronegativity (EN) - Measure of the relative tendency of an atom to attract electrons to itself when chemically combined with another atom. The higher the value of electronegativity, the more it tends to attract electrons toward itself. THE POLARITY OF THE BONDS BETWEEN ATOMS: Non-polar covalent bonds occur when electron pairs are shared equally or the difference in electronegativity between atoms is less than 0.5. Polar covalent bonds occur when electron pairs are unequally shared. The difference in electronegativity between atoms is significant. GROUP COLUMNS ARE SALLED NEBULA GROUPS. ‎ GIANT CLOUD OF GAS AND DUST KNOWN AS NEBULA. PERIODS ROWS ARE CALLED PERIODS. ‎ ROTOSTAR P ‎ IT IS FORMED FROM NEBULA DUE TO THE ‎ UCLEUS SYNTHESIS -CREATING N GRAVITY THAT PULLED HYDROGEN GAS SOMETHING NEW BY TOGETHER UNTIL IT SPINS FASTER AND FASTER AND BECOMES IGNITED. A COMBINING SEPARATE PROTOSTAR RISES. MATERIALS ‎ AIN SEQUENCE STAR M ‎ HEORIES -FORMATION OF T ‎ MAIN SEQUENCE STAR STARTS TO FORM GALAXIES, SOLAR SYSTEM AND WHEN NUCLEAR FUSION OCCURS AT THE OTHER HEAVENLY BODIES. CORE OF THE STAR. ‎ ED GIANT R ‎ IG BANG B ‎ THE STAR IS UNABLE TO GENERATE HEAT ‎ EDWIN HUBBLE COOLSDOWN AND GLOWS RED. ‎ THE HELIUM FUSED INTO CARBON. ‎ IG BANG NUCLEOSYNTHESIS B ‎ THE STAR IS NOW RED GIANT. ‎ PROCESS OF FORMING ATOMIC ‎ HITE DWARF W NUCLEI OTHER THAN ‎RED GIANT STAR BECOMES EXHAUSTED OF HYDROGEN'S LIGHTEST NUCLEAR FUEL, THE OUTER MATERIAL IS ISOTOPE DURING THE EARLY BLOWN OFF INTO SPACE LEAVING THE INERT UNIVERSE. CARBON. ‎ TELLAR NUCLEOSYNTHESIS S ‎ ASSIVE STAR M ‎ "STELLAR" MEANS STAR ‎ COOLS AND EXPANDS FASTER THAN LOW ‎ THE FORMATION OF ELEMENTS MASS STAR AND WILL TURN INTO RED SUPER IN THE CENTER OF THE STAR IS GIANT STAR, THE LARGEST KNOWN STAR. ‎ CARBON FUSION STILL OCCURS AND CALLED STELLAR OXYGEN FORMED. NUCLEOSYNTHESIS. ‎ EXPLOSION OF STAR OR SUPERNOVA ‎ CARL SAGAN SAID THAT "WE RELEASES LARGE AMOUNT OF ENERGY. ARE MADE OF STAR STUFF". ‎ NEUTRON STAR IS FORMED FROM SUPERNOVA EXPLOSION. ‎ ALSO THE SMALLEST STAR. ‎ BLACK HOLE IS A REGION IN SPACE WHERE GRAVITY IS TOO STRONG THAT NO MATTER CAN ESCAPE FROM IT.