Science Notes PDF

Element: A substance made of only one type of atom (e.g., oxygen, O₂). Compound: A substance made of two or more elements chemically bonded (e.g., water, H₂O). Pure substance: A material with a consistent composition, either an element or compound (e.g., gold or salt). Mixture: A combination of two...

Element: A substance made of only one type of atom (e.g., oxygen, O₂). Compound: A substance made of two or more elements chemically bonded (e.g., water, H₂O). Pure substance: A material with a consistent composition, either an element or compound (e.g., gold or salt). Mixture: A combination of two or more substances that are physically combined, not chemically bonded. Homogeneous mixture: A mixture with uniform composition throughout (e.g., saltwater). Heterogeneous mixture: A mixture with a non-uniform composition (e.g., sand and water). Groups: Vertical columns in the periodic table. Elements in the same group have similar chemical properties due to the same number of valence electrons. Periods: Horizontal rows in the periodic table. Elements in the same period have the same number of electron shells. Element symbol: A one- or two-letter abbreviation representing an element. Atomic number: The number of protons in an atom's nucleus, defining the element. Periodic table: A chart organizing elements by increasing atomic number and recurring chemical properties. Noble gases: A group of inert, non-reactive elements in Group 18 of the periodic table. They are stable Physical Properties of Matter Characteristics that can be observed or measured without changing the substance’s composition. Examples: Colour Odour Density Melting point Boiling point Solubility State (solid, liquid, gas) Chemical Properties of Matter Characteristics that describe a substance’s ability to undergo chemical changes and form new substances. Examples: Reactivity with other chemicals Flammability Acidity or basicity (pH)  Ability to rust or oxidise Decomposition Physical Changes of Matter Changes that affect the form or appearance of a substance but do not alter its chemical composition. You can bring it back Examples: Melting (solid to liquid) Boiling (liquid to gas) Freezing (liquid to solid) Condensation (gas to liquid) Breaking or cutting Dissolving Chemical Changes of Matter Changes that result in the formation of new substances with different chemical properties. Indicators include colour change, gas production, or heat/light emission You cannot bring back chemical change.. Examples: Burning (combustion) Rusting (oxidation) Digesting food Decomposition Reacting with acids or bases Reactivity: The ability of a substance to undergo chemical changes when interacting with other substances. Flammability: The ability of a substance to catch fire and burn in the presence of oxygen. Oxidation: A chemical reaction in which a substance loses electrons, often involving the addition of oxygen or the removal of hydrogen. Hydrogen (H): 1 Configuration: 1s¹ Helium (He): 2 Configuration: 1s² Lithium (Li): 3 Configuration: 1s² 2s¹ Beryllium (Be): 4 Configuration: 1s² 2s² Boron (B): 5 Configuration: 1s² 2s² 2p¹ Carbon (C): 6 Configuration: 1s² 2s² 2p² Nitrogen (N): 7 Configuration: 1s² 2s² 2p³ Oxygen (O): 8 Configuration: 1s² 2s² 2p⁴ Fluorine (F): 9 Configuration: 1s² 2s² 2p⁵ Neon (Ne): 10 Configuration: 1s² 2s² 2p⁶ Sodium (Na): 11 Configuration: 1s² 2s² 2p⁶ 3s¹ Magnesium (Mg): 12 Configuration: 1s² 2s² 2p⁶ 3s² Aluminium (Al): 13 Configuration: 1s² 2s² 2p⁶ 3s² 3p¹ Silicon (Si): 14 Configuration: 1s² 2s² 2p⁶ 3s² 3p² Phosphorus (P): 15 Configuration: 1s² 2s² 2p⁶ 3s² 3p³ Sulfur (S): 16 Configuration: 1s² 2s² 2p⁶ 3s² 3p⁴ Chlorine (Cl): 17 Configuration: 1s² 2s² 2p⁶ 3s² 3p⁵ Argon (Ar): 18 Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ Potassium (K): 19 Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ Calcium (Ca): 20 Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² Table for electric config 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d 6f 7s 7p 7d 7f