Unit 2: The Periodic Table CH1120

Structure of the Table Elements are arranged by increasing atomic number Remember this number tells us the number of protons in the nucleus Horizontal rows are called periods Vertical columns are called groups or families Elements of the same group have similar properties

Structure of the Table Periodic law states chemical and physical properties of the elements repeat in a regular, periodic pattern when they are arranged according to atomic number

Structure of the Table

Structure of the Table Group IA to VIIIA are called main group elements Group 1B to VIIIB are called transition metals Two rows below the table are called lanthanides and actinides

Structure of the Table Group IA are the alkali metals Group IIA are the alkaline earth metals Group VIIA are the halogens Group VIIIA are the noble gases (old term is inert gases)

Structure of the Table State whether the following are main group elements or transition metals Calcium Tungsten Nitrogen

Structure of the Table State what family the following belong to Bromine Sodium Magnesium Argon

Metals and Non-metals All elements can be classified as metals, non- metals, or metalloids

Metals Shiny luster Various colors, most are silvery Solids are malleable (thin sheets) and ductile (wire) Good conductors of heat and electricity Most metal oxides are ionic solids that are basic Tend to form cations in aqueous solution

Non-metals Do not have a luster Solids are usually brittle Various colors Solids are usually brittle Some hard some soft Poor conductors of heat and electricity Most non-metal oxides are molecular substances that form acidic solutions Tend to form anions or oxyanions in aqueous solution

Metalloids Have characteristics of both metals and non- metals (semi-metals) These are found on the “staircase” of the periodic table The only “staircase” element that is NOT a metalloid is aluminum B, Si, Ge, As, Sb, Te

Metals, Non-metals, Metalloids

Metallic Character Metallic character increases (H is exception) Moving top to bottom Moving right to left As metallic character decreases elements move from solid to liquid then to gas At room temperature the only liquid metal is mercury At room temperature the only liquid non-metal is bromine

Metallic Character

Semiconductors Solids with limited conductivity Two metalloids are semiconductors Si Ge

Group IA Alkali Metals Soft metallic solids Silvery, metallic luster High thermal and electrical conductivity Low densities and melting points Highly reactive with water Create ions with 1+ charge

Group IIA Alkaline Earth Metals Harder than alkali metals More dense and higher melting points than alkali metals Less reactive than alkali metals Create cations with 2+ charge Heavier elements give off characteristic colors when heated Fireworks; strontium = red, barium = green

Group VIIA Halogens Melting and boiling points increase with increasing atomic number At room temperature Fluorine and chlorine are gases Bromine is a liquid Iodine is a solid Diatomic elements (HOBrFINCl) Form X- halide ions (gain one electron)

Group VIIIA Noble Gases Previously called inert gases Mostly gases at room temperature Completely filled s and p subshells

Density Mass per unit volume 𝑑𝑒𝑛𝑠𝑖𝑡𝑦= 𝑚𝑎𝑠𝑠 𝑣𝑜𝑙𝑢𝑚𝑒 𝑑𝑒𝑛𝑠𝑖𝑡𝑦= 𝑚𝑎𝑠𝑠 𝑣𝑜𝑙𝑢𝑚𝑒 Density of atoms increases as you move to the lower left hand corner of the periodic table

Electron Configuration As we said before our electron configurations relate to the location on the periodic table We can divide the periodic table into s, p, d, and f sections Noble Gases, remember, always have all of the oribitals full Configurations end with a full p orbital

Electron Configuration

Bonding Elements interact to gain, lose, and share electrons Through these interactions atoms attempt to create stable electron configurations The electrons that are gained and lost are found in the outer most energy shell Valence electrons

Atomic Radius Based on the distance separating the nuclei when two atoms are bonded to each other Half the nucleus to nucleus distance between two bound atoms Used to measure size of atoms No defined boundaries Can only come so close to each other

Atomic Radius

Ionic Radius Ionic radius depends on: Charge Number of electrons Orbitals in which valence electrons are in For ions carrying the same charge, ionic radius increases as you move down a family

Ionic Radius Cations are usually smaller than their parent atoms Electrons removed from outer shell Anions are usually larger than their parent atoms Electrons added to outer shell

Ionic Radius

Ionization Energy Minimum energy required to remove an electron from the ground state of a gaseous atom or ion First and second ionization energies refer to first and second electrons being removed I1 < I2 < I3…

Ionization Energy

Electron Affinity Energy change that occurs when an electron is added to a gaseous atom or ion Measures the attraction of the atom for the added electron

Electron Affinity

Valence Electrons Remember as we move down a group we are adding a new energy level We can tell the number of valence electrons in main group elements Group number = valence electrons