Key Concepts in Chemistry

Definition: Chemistry is the scientific study of matter, its properties, composition, structure, reactions, and the changes it undergoes.

Organic Chemistry
- Focuses on carbon-containing compounds.
- Studies structure, properties, reactions, and synthesis of organic molecules.
Inorganic Chemistry
- Deals with inorganic compounds, typically those not based on carbon.
- Includes metals, minerals, and organometallic compounds.
Physical Chemistry
- Combines principles of physics and chemistry.
- Studies how matter behaves on a molecular and atomic level.
Analytical Chemistry
- Involves qualitative and quantitative analysis of substances.
- Techniques include chromatography, spectroscopy, and titration.
Biochemistry
- Studies chemical processes within and related to living organisms.
- Focuses on biomolecules like proteins, nucleic acids, lipids, and carbohydrates.

Atoms and Molecules
- Atoms: Basic units of matter; consist of protons, neutrons, and electrons.
- Molecules: Two or more atoms bonded together.
Elements and Compounds
- Elements: Pure substances made up of only one type of atom.
- Compounds: Substances formed when two or more different atoms chemically bond.
Chemical Reactions
- Process where substances (reactants) transform into new substances (products).
- Types include synthesis, decomposition, single replacement, and double replacement.

Organization
- Elements arranged by increasing atomic number.
- Groups (columns) share similar chemical properties.
- Periods (rows) indicate the number of electron shells.
Important Groups
- Alkali metals (Group 1)
- Alkaline earth metals (Group 2)
- Transition metals (Groups 3-12)
- Halogens (Group 17)
- Noble gases (Group 18)

Ionic Bonds
- Formed when electrons are transferred from one atom to another.
- Occurs between metals (donors) and nonmetals (acceptors).
Covalent Bonds
- Formed when atoms share electrons.
- Can be nonpolar (equal sharing) or polar (unequal sharing).
Metallic Bonds
- Involves the sharing of free electrons among a lattice of metal atoms.
- Responsible for properties like conductivity and malleability.

Solid
- Definite shape and volume.
- Particles are closely packed and vibrate in place.
Liquid
- Definite volume but takes the shape of its container.
- Particles are close but can move past each other.
Gas
- No definite shape or volume.
- Particles are far apart and move freely.

Acids
- Substances that donate protons (H⁺ ions).
- Taste sour, can conduct electricity, and turn litmus paper red.
Bases
- Substances that accept protons or donate hydroxide ions (OH⁻).
- Taste bitter, feel slippery, and turn litmus paper blue.

Law of Conservation of Mass
- Mass is neither created nor destroyed in a chemical reaction.
Avogadro's Law
- Equal volumes of gases, at the same temperature and pressure, contain an equal number of molecules.
Ideal Gas Law
- PV = nRT (where P = pressure, V = volume, n = moles, R = ideal gas constant, T = temperature).

Titration
- Method to determine concentration of a solution by reacting it with a solution of known concentration.
Filtration
- Separation technique used to separate solids from liquids or gases using a filter medium.
Chromatography
- Technique for separating components in a mixture based on differences in their movement through a stationary phase.

Organic Chemistry
- Studies carbon-containing compounds, including their structure, properties, and synthesis.
Inorganic Chemistry
- Focuses on inorganic compounds, generally those not based on carbon, such as metals and minerals.
Physical Chemistry
- Combines chemistry and physics to examine how matter behaves on molecular and atomic levels.
Analytical Chemistry
- Involves techniques for qualitative and quantitative analysis, including chromatography and spectroscopy.
Biochemistry
- Investigates chemical processes in living organisms, concentrating on biomolecules like proteins and nucleic acids.

Atoms and Molecules
- Atoms are the basic units of matter; molecules consist of two or more bonded atoms.
Elements and Compounds
- Elements are pure substances composed of one type of atom; compounds consist of two or more different atoms bonded together.
Chemical Reactions
- Transform reactants into products, including types like synthesis and decomposition.

Organization
- Elements are ordered by increasing atomic number, with groups sharing chemical properties and periods indicating electron shells.
Important Groups
- Includes alkali metals (Group 1), alkaline earth metals (Group 2), transition metals (Groups 3-12), halogens (Group 17), and noble gases (Group 18).

Ionic Bonds
- Formed by electron transfer between metals (donors) and nonmetals (acceptors).
Covalent Bonds
- Involve electron sharing, which can be nonpolar (equal sharing) or polar (unequal sharing).
Metallic Bonds
- Characterized by shared free electrons among metal atoms, contributing to conductivity and malleability.

Solid
- Has a definite shape and volume, with closely packed vibrating particles.
Liquid
- Has a definite volume and conforms to the shape of its container, with particles that can move past each other.
Gas
- Lacks definite shape and volume, with particles that are far apart and move freely.

Acids
- Donate protons (H⁺ ions), taste sour, and turn litmus paper red.
Bases
- Accept protons or donate hydroxide ions (OH⁻), taste bitter, feel slippery, and turn litmus paper blue.

Law of Conservation of Mass
- States mass is conserved in chemical reactions.
Avogadro's Law
- Equal volumes of gases at the same temperature and pressure contain the same number of molecules.
Ideal Gas Law
- Describes the relationship among pressure, volume, temperature, and moles of gas (PV = nRT).

Titration
- A method to find the concentration of a solution by reacting it with a known concentration solution.
Filtration
- Separates solids from liquids or gases using a filter medium.
Chromatography
- Separates components in a mixture based on their movement through a stationary phase.