2024 Science 9 - Unit 2 Notes PDF

Tipspromenad Notes Organization of the Periodic Table 1. Modern Periodic Table Organization: ○ The periodic table is primarily organized by atomic number (the number of protons in an atom). 2. History: ○ Dmitri Mendeleev is credited with developing the first periodic...

Tipspromenad Notes Organization of the Periodic Table 1. Modern Periodic Table Organization: ○ The periodic table is primarily organized by atomic number (the number of protons in an atom). 2. History: ○ Dmitri Mendeleev is credited with developing the first periodic table, organizing elements by atomic mass and leaving gaps for undiscovered elements. 3. Groups and Periods: ○ Groups: Vertical columns where elements share similar chemical properties. ○ Periods: Horizontal rows representing different electron energy levels. Characteristics of Elements 1. Metals: ○ General Characteristics: Malleable, ductile, shiny, and good conductors of heat and electricity. ○ Example: Iron (Fe) is a transition metal essential in steel production. ○ Special Groups of Metals: Alkali Metals (Group 1): Highly reactive, especially with water. Example: Potassium. Alkaline-Earth Metals (Group 2): Reactive but less so than alkali metals. Example: Magnesium. Transition Metals (Groups 3–12): Hard, shiny, and good conductors. Example: Iron. Post-Transition Metals: Less conductive and malleable. Example: Lead (used in batteries). 2. Non-Metals: ○ Characteristics: Brittle, poor conductors of heat and electricity. ○ Example: Oxygen (most abundant element in Earth’s crust). ○ Carbon: Known as the "building block of life," central to organic chemistry. 3. Semi-Metals (Metalloids): ○ Properties of both metals and non-metals. ○ Example: Silicon (used in solar cells and computer chips). 4. Noble Gases (Group 18): ○ Inert and non-reactive. ○ Examples:  Helium: Used in balloons and airships. Argon: Used in lights. 5. Halogens (Group 17): ○ Highly reactive non-metals, often found as diatomic molecules. ○ Example: Fluorine (highest electronegativity). 6. Chalcogens (Group 16): ○ Includes oxygen and other reactive elements. 7. Rare Earth Elements: ○ Found in the f-block. (inner transition metals) ○ Example: Lanthanum. Special Properties and Trends 1. States of Matter: ○ Most metals are solid at room temperature. ○ Exceptions: Mercury: Liquid metal used in thermometers. Bromine: Liquid non-metal. 2. Diatomic Elements: ○ Non-metals that naturally occur as diatomic molecules (e.g., halogens). 3. Electronegativity: ○ Fluorine has the highest electronegativity. 4. Lightest and Heaviest Elements: ○ Lightest: Hydrogen (most abundant in the universe). ○ Heaviest Naturally Occurring: Uranium. Periodic Trends and Bonding 1. Periodic Trends: ○ Observed due to changes in electron configuration, influencing reactivity, electronegativity, and ionization energy. 2. Chemical Bonds: ○ Ionic Bonds: Formed between metals and non-metals (e.g., NaCl). ○ Covalent Bonds: Formed by sharing electrons (e.g., H₂O). Uses and Applications of Elements 1. Common Uses: ○ Copper: Excellent conductivity, used in wiring. ○ Silicon: Used in glass, ceramics, and electronics. ○ Lead: High density, used in batteries.  ○ Gold (Au): Precious metal. 2. Applications of Noble Gases: ○ Helium: Balloons, airships. ○ Argon: Illumination. Discovery and Prediction 1. Gallium and Germanium: ○ Predicted by Mendeleev and later discovered, confirming his periodic table structure. 2. Natural Elements: ○ Number of Naturally Occurring Elements: 98. Quick Reference Facts 1. Liquid Elements: Mercury and bromine at room temperature. 2. Inner Transition Metals: The two rows at the bottom of the periodic table. 3. Gold: Symbol Au. 4. Bond Type: Ionic bonds typically form between metals and non-metals. Markus’ Notes Matter (interactions) make up → world matter = anything w/ mass; has space pure substance: element/compound; can’t be physically separated. mixture: 2+ substances that can be separated physically; each substance retains individual properties. elements: made of 1 type of atom; cannot be chemically broken down. compounds: made up of atoms of 2+ elements. physical properties: colour malleability texture viscosity conductivity state of matter melting point boiling point hardness solubility chemical properties: combustibility reactivity w/ acids reactivity w/ oxygen lack of reactivity. physical properties are observed/measured w/o changing chemical composition. chemical properties describe how something reacts w/ other substances. chemical reactions: 1+ pure substance(s) interact → form 1+ different substance(s). aka. atoms are rearranged + form different substance(s). they can form (more) complex compounds or break apart to form elements + simpler compounds. energy can be released in light/heat. elements are "building blocks" of matter. {matter w/ only 1 atom;} there’s 98 naturally occurring elements. on earth, ~90 elements occur naturally; many are synthesized in labs.  element names/symbols: ○ many element names come from Latin (e.g. lead = plumbum; sulfur = sulphurium) → others come from scientist’s/country names. ○ chemical symbols has 1 or 2 – an abbreviation. letters (unnamed synthetic elements are given placeholder names w/ 3 character symbols). 1st letter is capitalized; remaining letters are lowercase → e.g. C, Cu, Pb. elements are organized by their properties. ○ ~1860s, scientists tried to sort elements according to atomic mass. ○ Russian chemist, Dmitri Mendeleev made the earliest form of the periodic table. He wrote the properties of elements onto cards and reorganized them for months. He realized that he needed to leave gaps; he was able to accurately predict properties of unknown elements (at the time). He inferred that the missing elements would have similar properties to those of other elements in the family. The modern periodic table groups elements according to their atomic number – the number of protons in an atom. ○ each “box” also contains: chemical symbol + name, atomic mass and ion charge. The periodic table (PT) has 18 groups (columns) and 7 periods (rows). elements are classified as metals, non-metals, or semi-metals. metals are found on the left of the “zig-zag” line. they’re often silver or grey coloured, solid at room temperature; shiny, good conductors, malleable and ductile. alkali metals take up group 1 (except hydrogen); shiny, soft and highly reactive → water + oxygen. alkaline-earth metals are shiny + soft and reactive (not as much as alkali metals). transition metals (groups 3–12) are hard, shiny and good conductors; they are less reactive than alkaline earth metals. noble metals (found within transition metals) are rare + valuable because they resist corrosion + oxidation. post-transition metals are softer and less conductive than transition metals and often have lower boiling/melting points. lanthanides (rare earth metals): in the f-block, are silvery, shiny + used in specialized industries.  actinides (found below lanthanides) are mostly radioactive and unstable; few are found naturally. heavy metals are dense and toxic in large amounts. semi-metals (metalloids) have physical + chemical properties of metals and non-metals. e.g. they’re shiny solids (room temperature), but are brittle, not ductile and poor conductors. silicon, arsenic main-group elements: group 1, 2; 13–18. non-metals are generally gases, or brittle, dull-looking solids; poor conductors. halogens, in group 17, are extremely reactive and exist as diatomic molecules. Reactivity decreases down the group. noble gases (group 18) are extremely stable w/ full electron shells; colourless, odourless and inert under normal conditions. the oxygen group (aka chalcogens) - group 16 - vary in reactivity and decreases down the group. Most to least reactive groups: alkali metals (group 1) → halogens (group 17) → 7 valence electrons alkaline earth metals (group 2) chalcogens (group 16) → 6 valence electrons metalloids transition metals (groups 3–12) post-transition metals noble gases (group 18). Valence electron shell gives an atom stability if it’s full. Shell 1: 2 × e⁻ Shell 2: 8 × e⁻ Shell 3: 8 × e⁻ Unstable atoms will try to take/steal electrons because nitrogen is short 3 electrons. Its ion charge is -3 because it will try to steal 3 electrons from another atom and become an ion. Hailey’s Notes Science Test Review Ch. 2.1 and 2.2 1. **Matter** - Anything that has mass and takes up space. - Can be sorted into three categories: solid, liquid, gas - Solid: densest state of matter, molecules hold their shape, particles held so tightly together they are almost vibrating - Liquid: less dense than solid more dense than liquid, holds the shape of the container they are in, particles are flowing freely - Gas: least dense state of matter, particles take up all of the space in their container 2. **Pure Substance (Element vs Compound)** Element - A pure substance that cannot be broken down into simpler substances by physical or chemical means. - Example: oxygen, helium, hydrogen Compound - A pure substance of two or more elements; can be broken down into elements by chemical means. - Example: H2o, NaCl 3. **Mass** The amount of matter an object contains 4. **Mixture (Homogeneous vs. Heterogeneous)** - Homogeneous mixture: - Mixtures that are uniform throughout - Particles are evenly distributed and exactly alike - Heterogeneous mixture: - Mixtures that are not uniform throughout - Particles are not evenly distributed 5. **Periods and groups** - Groups: vertical columns - Periods: horizontal rows 6. **Metals, Semimetals (Metalloids), Non-metals** - Metals: - solid at room temperature except for mercury - Typically malleable (moldable) and ductile (able to be molded without losing toughness)  - Lustrous (shiny) - Good thermal conductivity - Good conductors of energy - Semimetals (Metalloids): - Elements with both the properties of metals and non-metals - Non-metals: - Poor conductor of electricity - Poor conductors of heat 7. **Isotopes** - Elements with the same amount of protons but different amounts of neutrons - They have the same chemical properties but different physical properties 8. **Demetri Mendeleev** - A russian chemist that created the periodic table - Demetri also accurately predicted the discovery of new elements and left the perfect about of spaces for those elements 9. **Alkali metals vs Alkaline Earth metals** Alkali metals - Group one on the periodic table - Highly reactive metals - Not found freely in nature - Lower density than other metals - Easily reacts with halogens Alkaline Earth metals - Group 2 on the periodic table - Two valence electrons 10. **Noble gases** - Elements which have an almost full valence shell making them neutral or unusually stable - The atoms do not lose/gain/share electrons with other elements - Helium for example has 2 valence electrons while the other noble gases have 8 electrons in the rest of their valence shells 11. **Physical v.s. Chemical properties** physical properties are characteristics of a substance that can be observed and measured without changing Chemical properties are the ability to react to other substances 12. **Halogens**  Group 17 on the periodic table 13. **Atoms** - Atoms are the smallest building blocks of matter 14. **Valence shell** The outer shells which hold the electrons of an element 15. **Atomic number** The number of protons in the nucleus of an atom