Understanding Chemistry: Formulas, Reactions, and Concepts

Introduction to Chemistry

Chemistry is the science of matter and its properties, including its composition, structure, physical properties, and reactivity. It involves observation, knowledge, and reasoning to deduce general principles and laws.

Types of Chemistry

1. Experimental:

• Natural: Physics, Chemistry, Biology
• Human: Geography, Politics, History

Formal: Mathematics and Logic

The scientific method involves observation, gathering information, forming a hypothesis, conducting experiments (with independent, dependent, and control variables), analyzing results, and developing a theory or law.

Conversions:

• 1 lb = 0.454 kg
• 1 in = 2.54 cm
• 1 in² = 6.45 cm²

Chemical Compounds

• Hydroacids (H + NM)
• Binary Salts (M + NM)
• Hydrides (M + H)
• Non-metal Oxides (NM + O)
• Metal Oxides (M + O)
• Oxyacids (H⁺ R^-) -ico
• Oxisales (M + R^-) -ato, -ito
• Hydroxides M⁺ (OH)^-

Chemical Reactions

1. Synthesis or Combination: A + B → C
2. Decomposition: A → B + C
3. Substitution or Displacement: A + BC → AC + B
4. Double Substitution: AB + CD → AD + CB

Formation of Compounds

• Metal Oxides: Metal + O₂ → Metal Oxide
• Non-metal Oxides: Non-metal + O₂ → Non-metal Oxide
• Bases (Hydroxides): Metallic Oxide + H₂O → Base (M-(OH))
• Oxyacids: Non-metallic Oxide + H₂O → Oxoacid (H-Rad)
• Binary Salt Hydrazide: Base + Acid → Binary Salt + H₂O
• Oxisal: Base + Oxoacid → H₂O + Oxisal
• Hydroacids: H₂O + Non-metal → H + Non-metal

Examples of Chemical Formulas

1. Sodium Chloride: NaCl
2. Calcium Bromide: CaBr₂
3. Nickel Nitride: Ni₃N₂
4. Lithium Sulfide: Li₂S
5. Barium Chloride: BaCl₂
6. Carbon Disulfide: CS₂
7. Barium Oxide: BaO
8. Calcium Hydroxide: Ca(OH)₂
9. Silver Chloride: AgCl
10. Lead Sulfate: PbSO₄

Valences

Common valences of elements:

• H, Li, Na, K, Ag, F: 1
• Ca, Ba, Be, Mg, Zn, O: 2
• B, Al: 3
• Si: 4
• Cu, Hg, Au: 1 and 2 (or 1 and 3 for Au)
• Cl, Br, I: 1, 3, 5, and 7
• Fe: 2 and 3
• N, P, Sb: 3 and 5
• Pb, C, Sn: 2 and 4
• S: 2, 4, and 6
• Cr: 3 and 6
• Mn: 1, 2, 4, 6, and 7

Nomenclature:

• 1V: -ico
• 2V: -oso (-), -ico (+)
• 3V: hipo-oso (-), -oso (=), -ico (+)
• 4V: hipo-oso (-), -oso (-), -ico (-/+), per-ico (+)

Properties of Matter

• Intensive: Do not depend on the amount of matter.
• Extensive: Dependent on the amount of matter.

Separation Techniques

• Filtration: Solid-liquid (heterogeneous)
• Decanting: Solid-liquid (heterogeneous)
• Chromatography: Homogeneous mixtures
• Evaporation: Solid-liquid (homogeneous)
• Distillation: Liquid-liquid
• Crystallization: Purification
• Magnetization: Solid-solid (homogeneous)
• Sedimentation: Solid-liquid

Atomic Models

• Dalton: Indivisible atom
• Thomson: Protons (+) and electrons (-) scattered
• Rutherford: Proton in a nucleus with electrons around it
• Bohr: Nucleus of protons and neutrons surrounded by electrons in orbits
• Chadwick: Discovered the neutron
• Millikan: Determined the charge of an electron

Isotopes and Isobars

• Example: 10p 14n = 24
• 12p 12n = 24 (Isotopes a, c, dybye)
• 10p 13n = 23 (Isobars aybcye)
• 10p 11n = 21
• 12p 11n = 23

Note: p = protons, n = neutrons, e = electrons, Z = atomic number, A = mass number