Chemistry Notes PDF

How it is Organized ​ Metals, Non-metals, and Metalloids: ○​ Metals: Good conductors of heat and electricity, malleable, ductile, and have high melting points (e.g., Iron, Copper). ○​ Non-metals: Poor conductors of heat and electricity, brittle, and have low melting...

How it is Organized ​ Metals, Non-metals, and Metalloids: ○​ Metals: Good conductors of heat and electricity, malleable, ductile, and have high melting points (e.g., Iron, Copper). ○​ Non-metals: Poor conductors of heat and electricity, brittle, and have low melting points (e.g., Oxygen, Nitrogen). ○​ Metalloids: Have properties of both metals and non-metals (e.g., Silicon, Boron). Properties of Chemical Families ​ Alkali Metals (Group 1): Highly reactive, especially with water. Soft and shiny. ​ Alkaline Earth Metals (Group 2): Less reactive than alkali metals, harder, and have higher melting points. ​ Halogens (Group 17): Very reactive, form salts with metals (e.g., Chlorine, Fluorine). ​ Noble Gases (Group 18): Inert gases, stable, and non-reactive (e.g., Helium, Neon). Periods vs Groups ​ Periods: Horizontal rows on the periodic table. Elements in the same period have the same number of electron shells. ​ Groups: Vertical columns on the periodic table. Elements in the same group have similar chemical properties due to the same number of valence electrons. Valence Electrons ​ The outermost electrons in an atom, involved in bonding. The number of valence electrons determines an element's chemical reactivity. Atoms & Ions ​ Atom: A neutral particle made of protons, neutrons, and electrons. ​ Ion: A charged particle formed when an atom loses or gains electrons. Positive ions are called cations, and negative ions are called anions. 2. Standard Atomic Notation ​ Atomic Number (Z): The number of protons in an atom. Determines the element. ​ Atomic Mass (A): The average mass of the element's isotopes. ​ Protons, Electrons, and Neutrons: ○​ Protons: Positive charge, found in the nucleus.  ○​ Electrons: Negative charge, found in electron clouds around the nucleus. ○​ Neutrons: Neutral charge, found in the nucleus. Bohr–Rutherford Diagram ​ Diagram showing electrons in energy levels around the nucleus. The number of electrons in each shell follows the 2n² rule. Example:​ Carbon (C)​ Atomic Number: 6​ Atomic Mass: 12​ Bohr-Rutherford Diagram: ​ 1st shell: 2 electrons ​ 2nd shell: 4 electrons 3. Ionic & Covalent Compounds Formation of Compounds ​ Ionic Compounds: Formed when atoms transfer electrons to achieve a full outer shell. Typically occur between metals and non-metals. ○​ Example: Sodium (Na) + Chlorine (Cl) → Sodium Chloride (NaCl). ​ Covalent Compounds: Formed when atoms share electrons. Typically occur between non-metals. ○​ Example: Hydrogen (H) + Oxygen (O) → Water (H₂O). Naming & Formula Writing ​ Ionic Compounds: Name the metal first, then the non-metal with its ending changed to "-ide". ○​ Example: NaCl → Sodium Chloride. ​ Covalent Compounds: Use prefixes to indicate the number of atoms (e.g., mono-, di-, tri-). ○​ Example: CO₂ → Carbon Dioxide. 4. Density Calculations ​ Density (ρ) = Mass/Volume  ○​ Units: g/cm³ or kg/m³ ​ Formula for calculating mass or volume: ○​ Mass = Density × Volume ○​ Volume = Mass/Density