Basic Concepts in Chemistry

Basic Concepts in Chemistry

• Atoms

  • Basic unit of matter.
  • Composed of protons, neutrons, and electrons.

• Elements

  • Pure substances consisting of one type of atom.
  • Organized in the Periodic Table (e.g., H, O, N).

• Compounds

  • Substances formed when two or more elements chemically bond.
  • Have distinct properties (e.g., water - H2O).

Chemical Bonds

• Ionic Bonds

  • Formed by the transfer of electrons from one atom to another.
  • Typically between metals and non-metals.

• Covalent Bonds

  • Formed when two atoms share electrons.
  • Usually between non-metals.

• Metallic Bonds

  • Occurs between metal atoms.
  • Involves a "sea of electrons" shared among many atoms.

States of Matter

• Solid

  • Definite shape and volume; particles closely packed.

• Liquid

  • Definite volume but takes the shape of its container; particles close but mobile.

• Gas

  • No definite shape or volume; particles far apart and move freely.

Chemical Reactions

• Reactants and Products

  • Reactants: substances that undergo change.
  • Products: new substances formed.

• Types of Reactions

  • Synthesis: A + B → AB
  • Decomposition: AB → A + B
  • Single Replacement: A + BC → AC + B
  • Double Replacement: AB + CD → AD + CB

• Balancing Reactions

  • Law of Conservation of Mass: matter is neither created nor destroyed.
  • Ensure equal number of each type of atom on both sides.

Acids and Bases

• Acids

  • Substances that donate protons (H⁺ ions).
  • Taste sour; turn blue litmus paper red.

• Bases

  • Substances that accept protons (or donate OH⁻ ions).
  • Taste bitter; turn red litmus paper blue.

• pH Scale

  • Measures acidity or basicity; ranges from 0 to 14.
  • pH < 7: Acidic; pH = 7: Neutral; pH > 7: Basic.

Stoichiometry

• Mole Concept

  • A mole represents 6.022 x 10²³ particles (Avogadro's number).
  • Used for quantifying substances in chemical reactions.

• Calculating Molar Mass

  • Add atomic masses of elements in a compound to find the molar mass.

Thermochemistry

• Energy Changes

  • Exothermic reactions release energy; feel hot.
  • Endothermic reactions absorb energy; feel cold.

• Enthalpy (ΔH)

  • Heat content of a system at constant pressure.
  • Positive ΔH: Endothermic; negative ΔH: Exothermic.

Organic Chemistry

• Hydrocarbons

  • Compounds made of carbon and hydrogen.
  • Types: Alkanes (single bonds), Alkenes (double bonds), Alkynes (triple bonds).

• Functional Groups

  • Specific groupings of atoms within molecules that give compounds distinct properties (e.g., alcohols -OH, carboxylic acids -COOH).

Laboratory Safety

• Personal Protective Equipment (PPE)

  • Always wear goggles, gloves, and lab coats.

• Chemical Handling

  • Know emergency procedures; label and store chemicals properly.

• Disposal of Chemicals

  • Follow guidelines for hazardous waste and non-hazardous waste disposal.

Basic Units of Matter

• Atoms are the fundamental building blocks of all matter, composed of protons, neutrons, and electrons.
• Elements are pure substances consisting of only one type of atom, and are organized on the Periodic Table (e.g., Hydrogen - H, Oxygen - O, Nitrogen - N).
• Compounds are formed when two or more elements chemically combine, resulting in substances with unique properties (e.g., water - H₂O).

Chemical Bonds

• Ionic bonds form when electrons are transferred from one atom to another, typically between metals and non-metals.
• Covalent bonds form when two atoms share electrons, usually between non-metals.
• Metallic bonds occur between metal atoms, involving a "sea of electrons" shared amongst many atoms.

States of Matter

• Solids have a definite shape and volume, with particles closely packed together.
• Liquids possess a definite volume but take the shape of their container, with particles closely packed but able to move around.
• Gases lack a definite shape or volume, with particles far apart and moving freely.

Chemical Reactions

• Reactants undergo a chemical transformation to become products, new substances formed in a chemical reaction.

• Synthesis reactions combine reactants to form a single product (A + B → AB).

• Decomposition reactions break down one reactant into multiple products (AB → A + B).

• Single replacement reactions involve one element replacing another in a compound (A + BC → AC + B).

• Double replacement reactions involve two reactants exchanging ions to form two new compounds (AB + CD → AD + CB).

• The Law of Conservation of Mass states that matter cannot be created or destroyed in a chemical reaction. This principle is used to balance chemical reactions, ensuring an equal number of each atom type appears on both sides of the equation.

Acids and Bases

• Acids donate protons (H⁺ ions) when dissolved in water. They taste sour and turn blue litmus paper red.
• Bases accept protons (or donate OH⁻ ions) when dissolved in water. They taste bitter and turn red litmus paper blue.
• The pH scale measures acidity and basicity, ranging from 0 to 14. Values below 7 represent acidic solutions, 7 is neutral, and above 7 are basic solutions.

Stoichiometry

• The mole is a unit used to quantify substances in chemical reactions, representing 6.022 x 10²³ particles (Avogadro's number).
• Molar mass is the mass of one mole of a substance, calculated by adding the atomic masses of all elements within the compound.

Thermochemistry

• Exothermic reactions release energy into the surroundings, often feeling hot, while endothermic reactions absorb energy from the surroundings, often feeling cold.
• Enthalpy (ΔH) represents the heat content of a system at constant pressure. A positive ΔH indicates an endothermic reaction, while a negative ΔH signifies an exothermic reaction.

Organic Chemistry

• Hydrocarbons are compounds composed solely of carbon and hydrogen.
• Alkanes contain only single bonds between carbon atoms, while alkenes have at least one double bond, and alkynes have at least one triple bond.
• Functional groups are specific arrangements of atoms within molecules, giving compounds distinct properties, such as alcohols (-OH), carboxylic acids (-COOH), and many others.

Laboratory Safety

• Personal Protective Equipment (PPE), including goggles, gloves, and lab coats, must be worn during laboratory work.
• Proper chemical handling involves understanding emergency procedures and following proper labeling and storage protocols.
• Chemical disposal follows specific guidelines for hazardous and non-hazardous waste, ensuring safe and environmentally sound practices.

This quiz covers fundamental concepts in chemistry, including atoms, elements, compounds, and chemical bonds. You'll explore various types of chemical bonds and the different states of matter. Test your understanding of these essential topics and their properties.