Periodic table Flashcards
Halogens
- Group of elements running from F to At
- all have 5 electrons in the p-orbital
- each element has the electrons present in the inert gas of its period
- At is a radioactive element with a short half life
Valence state and electronegativity
Valence State: It equals the charge of the atom.
Electronegativity: The strength with which a neutral atom attracts an electron.
Trend: Electronegativity increases across a period and decreases down a group.
Group 16 Elements: Require 2 additional electrons for a stable inert gas electronic structure.
Anions and cation
Ionization Potential: Energy required to remove an electron.
Anions vs. Cations: Forming negative anions is more difficult than forming positive cations.
Cations: Contract in size due to increased attractive pull.
Anions: Expand in size as the outermost electron is held less tightly.
Group 1 - Alkali Elements
Valence: Each neutral atom loses an electron, forming a +1 cation.
Example: H (hydrogen) forms H+ and combines with water to exist as H3O+.
Exception: Fr (francium) is a short-lived radioactive element.
Geochemical Properties: Exist in +1 cation in Earth environments.
Group 2 - Alkali Earth Elements
Valence: Neutral atoms lose 2 electrons to become a +2 cation.
Example: Ra (radium) is a radioactive element.
Water Reaction: Form alkaline solutions but react less vigorously with water than Group 1.
Group 18 - Noble Gases
Properties: Do not form chemical bonds with other elements.
Preference: Prefer to exist as gases, slightly soluble in water and igneous melts.
Inert: Rarely participate in chemical reactions.
Group 17 - Halogens
Gain Electron: Form anions by gaining electrons.
Exception: I (iodine) can form a 5+ valence state in the presence of oxygen.
Solubility: Similar solubilities to Group 1 alkali element cations.
Ionic Bonding - NaCl (Halite)
Structure: Na+ and Cl- ions arranged in an electrically neutral structure.
Crystal Structure: Must be electrically neutral overall.
Breaking Bonds: Relatively easy due to spherical symmetry of electron orbitals.
Electron Orbitals
S-Orbital: Perfectly spherical, holds 2 electrons.
P-Orbital: Forms 3 orthogonal dumbbells, holds 6 electrons.
D-Orbitals: Complex shapes, probability fields, hold 10 electrons.
Orbital Hybridization: Combining orbitals to form hybrid orbitals.
Boron (B)
Electron Configuration: 2 electrons in 1s, 2 in 2s, 1 in 2p.
Valence State: +3, forms B3+ cation.
Bonding: Often bound to OH- anions in solution.
Hybridization: Forms sp2 hybrid orbital with a trigonal planar shape.
Carbon (C)
Hybridization: Forms sp3 hybrid orbital with a tetrahedral shape.
Methane Molecule: Tetrahedral shape due to sp3 hybridization.
Alkaline Water Reaction: Forms sp3 hybrid orbital with tetrahedral shape.
Nitrogen (N)
Electron Configuration: Full 2p orbital or +5 cation.
Nitrate (NO3-): Forms sp2 hybrid orbital with a trigonal planar shape.
Ammonia (NH3): Forms sp3 hybrid orbital with a tetrahedral shape.
Lone Pair: Lone pair of electrons influences the shape of ammonia.
Phosphorus (P)
Electron Configuration: Forms +5 cation.
Phosphate (PO43-): Forms sp3 hybrid orbital with a tetrahedral shape.
Electronegativity: Greater electronegativity difference with O compared to N.
Transition Elements (group 3)
Scandium (Sc): Loses 3 electrons, forms Sc3+.
Group Behavior: Sc, Y, La lose 3 electrons to adopt an inert gas electronic structure.
Solubility: Generally insoluble as +3 cations but associate with some anions in seawater.
group 4 elements
Titanium (Ti): Forms +4 cation, found in ZrSiO4 (Zircon).
Properties: Ti is strong as steel but lighter, used in alloys.
Zircon: Durable mineral formed around 4.3 Ga.
Group 5 elements
High Field Strength Elements (HFSE): Zr, Nb, Hf, Ta.
Vanadium (V): Forms V5+ and V3+ oxidation states.
Solubility: HFSE are very insoluble and immobile in aqueous fluids.
Period 4 transition elements
Electronic Configuration: Fills 10 spaces in the d-orbitals.
Exception: Breaks in sequence at Cr and Cu.
Variable Charges: Some transition metals can form cations with different charges.
covalent bonding
Covalent Bonds: Electrons are shared between neighboring atoms.
Example: H2 molecule, N2 triple bond.
SiO4 Tetrahedron: Si and O covalently bond in a tetrahedral structure.
Rare Earth Elements (REE) - Lanthanides
Lanthanides involve filling seven different f-orbitals with complex shapes.
4 f-orbitals have eight lobes arranged symmetrically; 3 orbitals consist of a dumbbell with 2 rings.
Within Lanthanides, 4f-orbitals have lower energy than 6s- and 5d-orbitals.
Lanthanides Elements
La (Lanthanum) loses outermost 5d- and 6s-orbital electrons, adopting Xe inert gas structure.
Ce (Cerium) can form Ce3+ and Ce4+ cations based on oxygen availability.
Pr to Sm lose 5d- and 6s-orbital electrons, forming 3+ cations.
Eu forms a 3+ cation; Eu2+ is more soluble due to stable, spherical structure.
Gd to Lu all form 3+ cations; Ce4+ and Eu2+ are exceptions.
Lanthanides have similar geochemical properties useful in tracking processes in various environments.
Rare Earth Elements
All actinides are radioactive.
Th, Pa, and U occur naturally with known geochemical properties.
Np and Pu, mostly manmade, released through bomb tests and nuclear reprocessing.
Th behaves similarly to Ce, forming a very insoluble high field strength 4+ cation.
U can exist as a highly soluble U6+ or less soluble U4+ based on oxygen availability.
