Periodic Table Development & Structure

• Recap of key concepts

Development of the Periodic Table

• The periodic table's evolution spanned many years and involved scientists from various countries.
• Mendeleev arranged elements by increasing atomic mass.

Modern Periodic Table

• Henry G.J. Moseley determined the atomic numbers of elements using X-ray spectra in 1914.
• Moseley then arranged the elements by increasing atomic number.
• Mosely was killed in World War 1 at the age of 28 fighting in the Battle of Gallipoli in Turkey from 1887 -1915.

Structure of the Modern Periodic Table

• A horizontal row represents a period, and a vertical column represents a group.
• Groups 1, 2, and 13-18 are main group elements.
• Groups 3-12 are transition elements located in the middle of the table.
• The lanthanides and actinides are the two rows of 14 elements at the bottom.

Group Similarities

• Elements in the same group or family share similar electronic configurations as follows:
• Li: 1s²2s¹
• Na: 1s²2s²2p⁶3s¹
• K: 1s²2s²2p⁶3s²3p⁶4s¹
• Rb: 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s¹

Element Classification

• S-block elements are in groups 1A and 2A
• S orbitals are filled with electrons.
• Transition metals are d-block elements in the middle.
• D orbitals are filled with electrons.
• Lanthanides and actinides are elements where f orbitals are filled.

Finding Period and Group Numbers

• The period number corresponds to the maximum n value from the electronic configuration.
• Group number determination:
  • For s-block elements, it is the number of electrons in the ns orbital.
  • For p-block elements, it is the electrons in ns + np + 10.
  • For d-block elements, it is the electrons in ns + (n-1)d.
  • F-block elements consist of:
  • the 6th period from elements 58-71
  • the 7th period from elements 90-103.

Chemical Families

• Placement of elements 58 - 71 saves space on the Periodic Table.
• Placement of elements 90 - 103 saves space on the Periodic Table.

Alkali Metals (Group 1A)

• Alkali metals are in the first group.
• Alkali metals are very reactive.
• All alkali metals are metals except for Hydrogen.
• Alkali metals tend to form +1 ions.
• Alkali metals consist of soft, metallic solids.
• Alkali metals possess low densities and melting points, along with low ionization energies.
• Alkali metals are good conductors of electricity and heat.
• Alkali metals react with water to produce hydrogen and a metal hydroxide, resulting in an alkaline solution.

Alkaline Earth Metals (Group 2A)

• Alkaline Earth Metals are in the second group
• These metals are reactive and tend to form +2 ions.
• Oxygen compounds are strongly alkaline like Magnesium Oxide (MgO)
• Many are not water-soluble
• Beryllium (Be) does not react with water.
• Magnesium (Mg) reacts only with steam.
• Other alkaline earth metals react readily with water.
• Alkaline earth metals have higher densities and melting points than alkali metals.
• They exhibit low ionization energies, though not as low as alkali metals.
• Reactivity increases down the group.

Halogens (Group 17)

• Halogens are next to the last group on the right.
• Halogens are reactive and form diatomic molecules in their elemental state.
  • Fluorine (F2) and Chlorine (Cl2) are gases.
  • Bromine (Br2) is a liquid.
  • Iodine (I2) and Astatine (At2) are solids.
• Halogens form -1 ions with alkali metals, resulting in salts.
• Outer electrons move from the alkali metal to the halogen atom, forming an ionic halide(e.g. Sodium Chloride).

Halogen Reactivity

• Reactivity decreases in the following group as the atomic radius increases and the electron attraction decreases, as follows:
• Fluorine (F2) > Chlorine (Cl2) > Bromine (Br2) > Iodine (I2)

Noble Gases (Group 18)

• Noble gases are in the last group on the right.
• Noble gases include helium, neon, argon, krypton, xenon, and radon.
• Noble gases have a filled valence-electron configuration.
• Noble gases are rare and inert.
• Noble gases are monatomic gases that are chemically unreactive.
• Noble gases do not form charged ions since they have EA ≥ 0.

Metallic Character

• Metallic character decreases across a period with Francium increasing to the left and Fluorine decreasing to the right.
• Metallic character increases down a group with Francium increasing to the bottom to the left and Fluorine decreasing to the upper right.
• Francium is the best most metallic element.

Non-Metallic Character

• Non-metallic character increases across a period with Fluorine increasing to the upper right and Francium decreasing to the lower left..
• Non-metallic character decreases down a group with Fluorine increasing to the upper right and Francium decreasing to the lower left.
• Fluorine is the best non-metallic element.

Metal Properties

• Most elements are metals in the periodic table.
• Metals exhibit properties such as metallic luster, malleability, ductility, and hardness.
  • They shine and reflect light.
  • Malleable metals can be hammered or rolled into thin sheets.
  • Ductile metals can be drawn into wires.
  • Some metals are hard, like iron and chromium, while others are soft, like sodium, lead, and copper.

Metal Conductivity and Reactivity

• Metals conduct heat and electricity.
• Metals are typically solids at room temperature.
  • Mercury (Hg) is the only liquid metal at room temperature (melting point = -39 °C).
• Metal reactivity varies greatly; sodium (Na) and potassium (K) are very reactive.

Nonmetal Properties

• Nonmetals are brittle and pulverize when struck.
• Nonmetals are insulators because they do not conduct electricity and heat.
• Chemical reactivity of nonmetals varies: some are inert (noble gases), while others are reactive. -reactive nonmetals include F2, O2, and H2. -Non Mentals react with metals to form ionic compounds.

Metalloid Properties

• There are eight metalloid elements.
• These include Boron (B), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), Tellurium (Te), Polonium (Po), Astatine (At)
• They are positioned on a diagonal line between metals and nonmetals.
• Metalloids exhibit properties intermediate between metals and nonmetals.
  • They may have a metallic shine and can be brittle. -Metalloids are semiconductors because they conduct electricity, but not as well as metals. -Examples include silicon (Si) and germanium (Ge).

Thermodynamics Definition

• Thermodynamics is the study of energy flow into or out of a system during physical or chemical transformations.
• Concerned with the initial and final states of a system.
• Key properties are Temperature, Pressure, Volume, and Concentration
• It applies to macroscopic systems consisting of bulk matter.
• It ignores microscopic systems like the internal structure of atoms and molecules.

Thermodynamics Application

• The study of thermodynamics concerns the ways energy is stored with in a body including:
  • Energy Transformations
  • Heat
  • Work

Thermodynamic System Definitions

• A thermodynamic system is part of the universe under study.
• The surrounding is the rest of the universe.
• A boundary is a real or imaginary surface separating the system from the surroundings.
• The boundary type determines the system type.

System Types

• A homogeneous system is uniform throughout and has only one phase.
• A phase is a homogeneous, physically distinct, and mechanically separable portion of a system.
• A heterogeneous system has two or more phases being something that does not maintain uniformity throughout.

Types of Thermodynamic Systems

• An isolated system cannot transfer matter or energy to its surroundings.
• A closed system cannot transfer matter but does transfer energy in the form of heat, work, and radiation to its surroundings.
• An open system is able to transfer both energy and matter to the surroundings.

Boundaries

• A diathermic boundary/system permits thermal energy transfer into and out of the system.
• An adiabatic boundary/system prevents thermal energy transfer into and out of the system.

Properties

• Macroscopic properties are divided into two classes: intensive and extensive
• Intensive properties do not depend on the quantity of matter.
• Extensive properties depend on the quantity of matter.

Properties cont.

• Intensive Properties:
  • Pressure
  • Temperature
  • Density
  • Concentration
  • Boiling Point
  • Surface Tension
  • Freezing point
  • Viscosity
  • Molar Mass
  • Specific heat capacity
  • Mole Fraction
• Extensive Properties:
  • Mass
  • Volume
  • Number of Moles
  • Internal Energy
  • Enthalpy
  • Entropy
  • heat Capacity
  • Gibbs' Free Energy
• Extensive properties are additive

State of a System

• A thermodynamic system is in a certain state when all its properties are fixed or known.
• The fundamental properties are pressure (P), temperature (T), volume (V), mass, and composition.
• Properties are referred to as state variables, functions, or thermodynamic parameters.
• A change of system from the initial state to the final state will be accompanied by change in the state variables

Total Energy of a System

• The sum of all forms of energy (thermal, mechanical, kinetic, potential, electrical, magnetic, chemical, and nuclear) that can exist in a system.
• Generally the sum of internal, kinetic, and potential energies.

Equations

• E = U + KE + PE
• E = system total energy
• U = internal energy
• KE = kinetic energy = mV²/2
• PE = potential energy = mgz

Properties of Equilibrium

• A system characteristic that is in equilibrium
• Types include:
  • Vary directly with system size.
  • Volume, Mass, Total Energy

Equilibrium of a System

• A system that is not undergoing any change.
• All properties of the system are known and are not changing.
• If one property changes, then the state of the system changes.
• "Equilibrium" is defined as a state of balance.
• A system is in equilibrium if it maintains thermal (uniform temperature), mechanical (uniform pressure), phase (mass of two phases), and chemical equilibrium.

Processes and Paths

• A process is when a system changes from one equilibrium state to another.
• Special processes include:
  • Isobaric meaning constant pressure.
  • Isothermal meaning constant temperature.
  • Isochoric meaning constant volume Isoentropic means constant entropy
• series of states which a system passes through during a process

State Variables

• An important characteristic of a state variable is that when a system state is alerted, the change of the variable depends on the initial and final state(s) of the system.
• Heating a sample of water from 25° C to 100° C is equal to the difference is temperatures.
• The state variable is independent of the path or process in the following formula:
• ΔT = Tfinal - Tinitial = 75°C

Equations of State

• It is unnecessary to state all the state variables to define a particular system.
• Where P and T define values and have a fixed automatic value for a single pure gas
  • If P and T are specified, the value of the third (V) is fixed automatically and can be calculated from the equation of state.
• The variables (P and T) must be specified to define the state of the system since they are called independent state variables.

Equations

• PV = RT in which R is the fixed gas constant.
• The remaining state variable (V) is dependent and called dependent state variable.