G8 3rd Quarter Science Reviewer PDF

SCIENCE QUARTER 3 REVIEWER Legend: Green highlight - Examples and definitions Orange highlight - Lesson Yellow highlight - Important Purple text - Processes, names, etc. Blue text - Titles Lesson 1: Physical Change of Matter Phase Change -​ The process of changing from one physical state to an...

SCIENCE QUARTER 3 REVIEWER Legend: Green highlight - Examples and definitions Orange highlight - Lesson Yellow highlight - Important Purple text - Processes, names, etc. Blue text - Titles Lesson 1: Physical Change of Matter Phase Change -​ The process of changing from one physical state to another. Phase Change of Matter ​ Melting -​ Solid to liquid -​ When a solid absorbs enough energy to overcome the force holding its particles together. It is said to be heated. -​ Melting point is achieved. ​ Freezing or Solidification -​ Liquid to solid This process allows particles to get closer to a rigid position. The particles can no longer move freely; instead they will just vibrate. -​ Freezing point is achieved. ​ Evaporation -​ Liquid to gas -​ Liquid absorbs energy when heated, the particles will become separated, particles have less attraction allowing them to move freely. ​ Condensation -​ Gas to liquid Gas loses heat, the particles press in on each other and roll over. ​ Sublimation -​ Solid to gas Ex. dried ice ​ Deposition -​ Gas to solid  Ex. Frost Lesson 2: The Atomic Structure Democritus and Leucippus -​ In 460–371 B.C.E., they presented the concept that all matter is made up of invisible particles in which they called “atomos” which means uncuttable. -​ Aristotle - believed that all things can be divided infinitely. John Dalton -​ In 1803, John Dalton presented his atomic theory. Dalton's Atomic Theory: 1.​ Matter is made up of very small, invisible and indivisible particles called atoms. 2.​ Atoms of the same element have the same properties. 3.​ Atoms cannot be created nor destroyed in any chemical reaction. 4.​ Atoms combine with each other in whole number ratios to produce compounds. William Crookes -​ Invented the Crookes Tube in 1869 -​ Tube was filled with gas and features positive (anode) and (cathode electrodes. -​ Cathode rays - streams of electrons Wilhelm Roentgen -​ He used the Crookes Tube in 1895 and discovered a new kind of radiation which he called x-ray and used it in the medical field. Joseph John Thomson (J.J Thomsom) -​ Concluded that cathode rays were composed of very light, negatively charged particles called corpuscles. *Electrons - negatively chared corpuscles. -​ He discovered the negatively charged particles which he called corpuscles, then later was replaced as electrons. (coined by G. Johnstone Stoney in 1891 but in 1897, Geaorge Francis Fitzgerald suggested that corpuscles be replaced to electron.) Raisin Bread or Plum Pudding Model -​ Atom is likely a positively charged sphere with embedded negative particles. -​ Disapproved the idea of an indivisible atom. Max Planck -​ Quanta (singular:quantum) -​ Different atoms and molecules can emit or absorb energy in discrete quantities only. -​ The smallest amount of energy that can be emitted or absorbed in the form of electromagnetic radiation is known as quantum. Eugen Goldstein -​ Discovered the positive particle and called it H+ Ernest Rutherford -​ Discovered the positively charged particles called protons. Alpha-particle Scattering Experiment -​ Used the positively charged alpha particles to be beamed directly towards a thin foil of gold, silver or copper. Results: 1.​ Over 98% of alpha particles went through the foil 2.​ About 2% deflected 3.​ A few recoiled back to the source 4.​ -​ Revealed that there is a tiny, dense and positively charged center of the atom called the nucleus. *He invented the gold leaf device which helped in his alpha-particle experiment that led to his discovery of the nucleus. He is known as the proton discoverer. Niels Hendrik David Bohr -​ Bohr Model or Shell Model -​ Electrons could jump from a higher-energy orbit to a lower one, emitting a quantum of light called a proton. Schrödinger -​ In 1926, he proposed a new model called the Quantum-wave Model based on the studies of Bohr. -​ His model depicts electrons as undulations of matter. It describes the wave behavior of the electron. James Chadwick -​ Announced the presence of a neutral particle inside the nucleus called neutron. Main Subatomic Particles Protons -​ Found in the nucleus -​ Has a positive electrical charge of positive one (+1) -​ Has a mass of 1 atomic unit (amu) which is about 1.673 × 10^-27 kg. -​ Symbol: p+ -​ Defines the identity of an element. Electrons -​ The negatively charged particles 3 Fundamental Properties 1.​ Charge -​ Electric charge of -1 2.​ Mass -​ 9.109×10^-31 kg 3.​ Spin -​ e- Neutrons -​ Carry no electrical charge -​ Has a mass of 1.675 × 10^-27 kg -​ Approximately 1 amu or nearly equal to the mass of a proton. Atomic number -​ Number of protons -​ “Atoms of the same elements have the same number of protons and those of different elements have the same number of protons.” -​ Determines the position of the element in the periodic table. -​ Provides the number of electrons for a neutral atom. Mass Number and Atomic Mass -​ Mas is the sum of the number of protons and the number of neutron in an atom. (Nucleons) -​ Also the atomic number rounded off to a whole number. -​ The atomic mass is measured in atomic mass unit (amu). -​ A = p + n Mass Number -​ While the number of protons remain the same in all atoms of an element, the number of neutrons can vary. Thus, atoms of the same element can have different mass numbers called isotopes. Notation of an Atom X = Element A = Mass number (p+n) Z = Atomic number/No. of protons  🙏) Lesson 3: Periodic Table of Elements (Wala na pong highlights kasi tinamad na at wala na po akong oras Arrangement of the Elements -​ Arranged horizontally in the order of increasing atomic numbers. -​ Each element is identified by its symbol placed at the middle of the square; atomic number and mass number are also included. Period or Series -​ The horizontal rows of elements. -​ Represents the main energy levels. Period 1 -​ 2 elements corresponding to the number of electrons in s-sublevel. Periods 2 & 3 -​ Each have 8 elements -​ In s and p sublevels Periods 4 & 5 -​ 18 elements -​ s, p and d sublevels Periods 6 & 7 -​ 32 elements -​ s, p, d and f sublevels *Period 6 - Lanthanide series *Period 7 - Actanide series Groups or Families -​ Vertical columns of elements -​ Calssified into A and B families, each consists of 8 groups. *Group A - Representative elements *Group B - Transition elements Group IA -​ Alkali metals -​ Most active Group IIA -​ Alkaline Earth Metals -​ Less reactive metals  -​ Mineral ores. Group IIIA -​ Boron family or aluminum group -​ Fairly reactive Group IVA -​ Carbon group -​ Consist of a nonmetal, metalloid, and metals. Group VA -​ Nitrogen group -​ Consist of a nonmetal, metalloid, and metals. Group VIA -​ Oxygen group o chalcogens -​ Consist of a nonmetal, metalloid, and metals. Group VIIA -​ Halogens (salt formers) -​ All members are nonmetals and are among the most reactive of all elements. Group VIIIA -​ Noble gasses/rare gasses/Group D -​ Not very abundant on earth and least reactive elements. -​ Noble refers to elements’ general lack of reactivity. Group B or Family B -​ Transition elements -​ Found in between Group IIA and Group IIIA Inner transition group -​ Lanthanide and Actanide series -​ Found at the bottom of the table The Blocks of Elements S-block -​ Consists of two groups, Group 1A & Group IIA. -​ Valence electron in the s-orbital. P-block -​ Group IIIA - Group VIIIA -​ Valence electron in p-orbital. D-block -​ Group IIIB - Group IIB -​ Valence electron in d-orbital. F-block -​ 28 elements belonging to the inner transition group. -​ Valence electron in f-orbital. Valence electrons - At the outermost shell; involved in chemical reactions. Electron - Outermost energy shell. Lesson 4: The Development of the Periodic Table Jons Jacob Berzelius -​ Developed a table of atomic weights and system of modern chemical symbols. Johann Dobreiner -​ Arranged the elements into triads, where 3 elements with similar properties are grouped together. John Newlands -​ Law of Octaves Dmitri Mendeleev and Julius Lothar Meyer -​ Both arranged the elements in order of increasing atomic mass while putting in groups those with similar properties. *Mendeleev became known for his periodic law. Henry Moseley -​ Modern Periodic Law which states that “the properties of elements vary periodically with atomic number”. Lesson 5: Reactivity Series Periodic Trends -​ Patterns in the properties of elements that are dependent on its position in the periodic table. -​ Electrons play the most role in determining the physical and chemical properties of an element. -​ Number and positions of electrons in the outermost energy level (valence electrons) identify element group number and the highest main energy level. Trends in properties of the element that follow a pattern down a group and across a group in the periodic table. Metallic Characters -​ Level of reactivity -​ How easy for an atom to lose an electron. -​ Tends to lose electron (cation). -​ Increases from top to bottom and right to left -​ Group IA - most active -​ Most reactive metals or elements are found in the lower portion of the periodic table. Nonmetallic Characters -​ How easy it is to gain an electron. -​ High attraction for electrons. -​ Increases from bottom to top and from left to right. -​ The ease and speed with which the metal reacts with another substance.