Chemistry: Atoms, Molecules, and Reactions

ATOMS AND NUCLEUS

• Components of Atom:
  • Proton:
  • Charge: +1
  • Mass: 1
  • Neutron:
  • Charge: 0
  • Mass: 1
  • Electron:
  • Charge: -1
  • Mass: 0
• Electron Shells:
  • Inner shell holds 2 electrons
  • Outer shell holds 8 electrons
• Atomic Number:
  • Represents the number of protons
• Mass Number:
  • Sum of protons and neutrons (always a whole number)
• Relative Atomic Mass (RAM):
  • Average of isotopes, accounting for abundance; not a whole number
• Calculating Number of Neutrons:
  • Number of neutrons = Mass number - Atomic number

ELECTRON CONFIGURATION

• Counting Electrons in Shells:
  • Example: Lithium = 2,1
• Periodic Trends:
  • Period:
  • Horizontal rows indicate the number of shells for each element
  • Group:
  • Vertical columns indicate the number of electrons in the outer shell
• Reactivity Trend:
  • Fewer outer electrons + more distance from nucleus -> higher reactivity

ISOTOPES

• Definition:
  • Atoms of the same element with different numbers of neutrons, affecting mass number
• Relative Atomic Mass Formula:
  • RAM = (mass of iso1 × abundance%) + (mass of iso2 × abundance%)/100

REACTIONS IN GROUPS

• Group 1 (Alkali Metals):
  • Reactivity increases down the group as they lose electrons to achieve a full outer shell
• Group 7 (Halogens):
  • Reactivity decreases down the group as they gain electrons and experience electron shielding
• Both groups aim for stable electron configuration (a full outer shell of 8 electrons)

TRANSITION METALS

• Ion Formation:
  • Can form ions with different charges unlike other metals which typically form + ions
• Metal Properties:
  • Good conductors of heat and electricity
  • High melting points
  • Ductile, malleable, sonorous, shiny, and some are magnetic
• Transition Metal Compounds:
  • Formed when two or more elements chemically combine
  • Often change color and are used as catalysts

HALOGENS AND NOBLE GASES

• Halogens (Group 7):
  • Exist as diatomic molecules to achieve full outer shells (covalent bonds)
• Noble Gases (Group 0):
  • Inert due to full outer shells, do not react easily

BALANCING EQUATIONS

• Example Reactions:
  • Lithium + Water -> Lithium Hydroxide + Hydrogen
  • Sodium + Water -> Sodium Hydroxide + Hydrogen

SOLUTIONS AND SEPARATION TECHNIQUES

• Definitions:
  • Solvent: Liquid in which solute dissolves
  • Solute: Solid that dissolves
  • Solution: Mixture of solute and solvent
  • Soluble/Insoluble: Ability to dissolve or not
• Separation Techniques:
  • Filtration: Separate solute from solution
  • Evaporation: Liquid to gas transition
  • Distillation: Separates solvent from solution due to different boiling points
  • Chromatography:
  • Separates dissolved substances, with stationary and mobile phases
  • RF Value calculation: RF = (distance traveled by substance)/(distance traveled by solvent)

FRACTIONAL DISTILLATION OF CRUDE OIL

• Crude oil is heated, causing evaporation
• Different compounds condense at varying temperatures based on boiling points

CHEMICAL REACTIONS

• Metal + O2 = Metal Oxide
  • Indications: burning/glowing, color change, smoke
• Metal + Acid = Salt + Hydrogen
  • Observations: fizzing/pop or violent reactions with very reactive metals
• Metal + H2O = Metal Hydroxide + Hydrogen
  • Observations: fizzing, movement

CRYSTALLIZATION

• Pure salt crystals formed by evaporating a solution until saturation is reached

REACTIVITY SERIES AND DISPLACEMENT REACTIONS

• Example Reactions:
  • Mg + FeSO4 = MgSO4 + Fe
  • Cu + FeSO4 = Cu + FeSO4
• Ion Charge Basics:
  • Positive ions = cations (typically metals)
  • Negative ions = anions (typically non-metals)

REDOX REACTIONS

• Definition:
  • Simultaneous oxidation (loss of electrons) and reduction (gain of electrons)
• Example Reaction: ZnO + Mg -> Zn + MgO
  • Oxidation: Mg -> Mg2+ + 2e-
  • Reduction: Zn2+ + 2e- -> Zn

HALF EQUATIONS

• Process:
  • Ensure same number of atoms on each side
  • Write changes and add electrons accordingly

ALLOYS AND RUSTING

• Alloys:
  • Mixtures of two or more metals or metals with non-metals
• Rusting:
  • Occurs in iron and its alloys when both oxygen and water are present
  • Reaction: Iron + Oxygen + Water -> Hydrated Iron (III) Oxide
• Aluminum Reactivity:
  • Forms protective layer when reacting with air

CORROSION PREVENTION

• Methods:
  • Paints or plastic coatings
  • Electroplating
  • Oiling or greasing
  • Sacrificial methods (using more reactive metals for coating)

ORES AND EXTRACTION METHODS

• Ore Definition:
  • Natural rocks or minerals with valuable metals or elements present
• Extraction Methods:
  • Carbon in blast furnace for less reactive metals
  • Electrolysis for more reactive metals
  • Ions are attracted to respective electrodes for reduction (positive) and oxidation (negative)

POLYMERS

• Definition:
  • Large molecules formed from repeated monomers
• Types of Polymers:
  • Thermosoftening Polymers:
  • Flexible, can be remolded when heated
  • Thermosetting Polymers:
  • Hard and rigid, do not melt but char upon heating
• Polymer Types:
  • Low Density Poly(ethene): Flexible, used for bags and bottles
  • High Density Poly(ethene): Rigid, used for tanks and pipes
• Conditions to Change Properties of Polymers:
  • Reaction temperature, pressure, and catalyst