Introduction to the Periodic Table

• Chemistry is the study of matter, its properties, and how it changes
• Matter has mass and takes up space

The Periodic Table

• The periodic table arranges elements by increasing atomic number
• Elements in the same vertical column (group) share similar properties

Organization of the Periodic Table

• Periods are horizontal rows
• Groups are vertical columns, also known as families
• Elements within the same group exhibit similar chemical behaviors

Metals

• Metals are lustrous, malleable, ductile, and conduct heat and electricity well
• Most elements are metals
• Metals are on the left side of the periodic table

Nonmetals

• Nonmetals are brittle and poor conductors of heat and electricity
• Nonmetals are located on the right side

Metalloids

• Metalloids have both metallic and nonmetallic properties
• Metalloids are located along the staircase line separating metals and nonmetals

Groups in the Periodic Table

• Group 1: Alkali metals (Li, Na, K, Rb, Cs, Fr) are very reactive and form +1 ions
• Group 2: Alkaline earth metals (Be, Mg, Ca, Sr, Ba, Ra) are reactive and form +2 ions
• Group 17: Halogens (F, Cl, Br, I, At) are very reactive nonmetals and form -1 ions
• Group 18: Noble gases (He, Ne, Ar, Kr, Xe, Rn) are generally inert due to full valence shells

Key Properties of Elements

• Atomic number is the number of protons
• Mass number is the total number of protons and neutrons
• Isotopes are atoms of the same element with different numbers of neutrons

Ions

• Ions form when atoms gain or lose electrons
• Cations are positive ions formed by losing electrons
• Anions are negative ions formed by gaining electrons

Chemical Bonds

• Chemical bonds hold atoms together in molecules or compounds
• Ionic bonds involve electron transfer
• Covalent bonds involve electron sharing

Electronegativity

• Electronegativity measures an atom's ability to attract electrons in a bond
• Electronegativity increases across a period and decreases down a group

Chemical Reactions

• Chemical reactions rearrange atoms and molecules
• Reactants undergo change
• Products are formed

Balancing Chemical Equations

• Balancing ensures the same number of atoms of each element on both sides
• Balancing follows the law of conservation of mass

Stoichiometry

• Stoichiometry is the quantitative study of reactants and products
• Balanced equations are used to calculate amounts of reactants and products

Mole Concept

• A mole contains as many entities as there are atoms in 12 grams of carbon-12
• One mole equals Avogadro's number (6.022 x 10^23)

Molar Mass

• Molar mass is the mass of one mole, in grams per mole (g/mol)
• Molar mass is numerically equal to atomic or molecular weight

Solutions

• A solution is a homogeneous mixture
• The solute is dissolved in the solvent
• The solvent does the dissolving

Concentration

• Concentration is the amount of solute in a given amount of solvent or solution
• Molarity (M) is moles of solute per liter of solution

Acids and Bases

• Acids donate protons (H+) in aqueous solutions
• Bases accept protons (H+) in aqueous solutions

pH Scale

• The pH scale measures acidity or basicity; values range from 0 to 14
• pH < 7 is acidic
• pH = 7 is neutral
• pH > 7 is basic

Redox reactions

• Redox reactions (oxidation-reduction reactions) involve electron transfer
• Oxidation is loss of electrons
• Reduction is gain of electrons
• The reducing agent loses electrons and is oxidized
• The oxidizing agent gains electrons and is reduced

Electrochemistry

• Electrochemistry studies chemical reactions that cause electron movement
• It deals with interconversion of electrical and chemical energy

Electrochemical Cells

• Electrochemical cells convert chemical energy into electrical energy, or vice versa
• Two main types: galvanic (voltaic) and electrolytic

Galvanic Cells

• Galvanic cells (voltaic cells) use spontaneous redox reactions to generate electricity
• They consist of two half-cells, each containing an electrode in an electrolyte solution
• Oxidation occurs at the anode (negative electrode)
• Reduction occurs at the cathode (positive electrode)

Electrolytic Cells

• Electrolytic cells use electrical energy to drive non-spontaneous redox reactions
• They consist of two electrodes in an electrolyte solution
• Oxidation occurs at the anode (positive electrode)
• Reduction occurs at the cathode (negative electrode)

Cell potential

• Cell potential (Ecell) measures the potential difference between half cells
• It drives electrons from anode to cathode
• A positive cell potential indicates a spontaneous reaction (galvanic cell)
• A negative cell potential indicates a non-spontaneous reaction (electrolytic cell)

Standard Reduction Potentials

• Standard reduction potential (E°) measures the tendency to be reduced
• Standard conditions: 298 K, 1 atm, 1 M
• Used to calculate cell potential
• A larger standard reduction potential indicates greater tendency to be reduced

Nernst Equation

• The Nernst equation relates cell potential (Ecell) to standard cell potential (E°cell) and the reaction quotient (Q)
• Used to calculate cell potential under non-standard conditions

Electrolysis

• Electrolysis used electrical energy to drive non-spontaneous reactions
• Commonly used to decompose compounds into elements
• Applications include electroplating, metal refining, and production of chemicals

Corrosion

• Corrosion is the deterioration of metal due to chemical reactions with the environment
• It's an electrochemical process involving metal oxidation
• Examples: rusting of iron, tarnishing of silver