Periodic table

Question 1

Halogens

Answer 1

• 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

Question 2

Valence state and electronegativity

Answer 2

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.

Question 3

Anions and cation

Answer 3

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.

Question 4

Group 1 - Alkali Elements

Answer 4

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.

Question 5

Group 2 - Alkali Earth Elements

Answer 5

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.

Question 6

Group 18 - Noble Gases

Answer 6

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.

Question 7

Group 17 - Halogens

Answer 7

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.

Question 8

Ionic Bonding - NaCl (Halite)

Answer 8

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.

Question 9

Electron Orbitals

Answer 9

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.

Question 10

Boron (B)

Answer 10

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.

Question 11

Carbon (C)

Answer 11

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.

Question 12

Nitrogen (N)

Answer 12

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.

Question 13

Phosphorus (P)

Answer 13

Electron Configuration: Forms +5 cation.
Phosphate (PO43-): Forms sp3 hybrid orbital with a tetrahedral shape.
Electronegativity: Greater electronegativity difference with O compared to N.

Question 14

Transition Elements (group 3)

Answer 14

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.

Question 15

group 4 elements

Answer 15

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.

Question 16

Group 5 elements

Answer 16

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.

Question 17

Period 4 transition elements

Answer 17

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.

Question 18

covalent bonding

Answer 18

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.

Question 19

Rare Earth Elements (REE) - Lanthanides

Answer 19

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.

Question 20

Lanthanides Elements

Answer 20

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.

Question 21

Rare Earth Elements

Answer 21

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.