Chapter 2 Flashcards
Modern periodic table arranges elements into …
periods (rows) and groups/families (columns) based on atomic number
A Elements (Representative Elements)
Groups IA through VIIIA
* Valence electrons in orbitals of s or p subshells
B Elements (Nonrepresentative Elements)
Transition elements, lanthanides, actinides
Metals
- Left side and middle of PT
- Active metals, transition metals, lanthanides, actinides
- Lustruous (shiny) EXCEPT for mercury
- High melting points and densities EXCEPT for lithium
- Deform without breaking
- Malleable (hammered in to shapes
- Ductility (can be pulled or drawn in to wires
- Low electronegativity, high electropositivity
- Large AR
- Small IR
- Good conductors
Nonmetals
- Upper right of PT
- Brittle
- No luster
- High ionization energy and electronjegativity
- Small AR
- Large IR
- Poor conductors
- Negative oxidation states
Metalloids/Semimetals
- Characteristics of metals and nonmetals
- Form staircase on PT
- B, Si, Ge, As, Sb, Te, Po, At
Effective Nuclear Charge (Zeff)
Electrostatic attraction between valence shell electrons and nucleus
* Net + charge experienced by outermost electrons
* Increases left to right and up
Principal Quantum Number Trend
Increases as moves down PT
Atomic Radius
1/2 the distance between centers of two atoms of an element that are briefly in contact
* Increases right to left and down
Ionic Radii
Ionization Energy (IE)/Ionization Potential
Energy required to remove an electron from a gaseous species
* Endothermic process (requires heat)
* Increases left to right and up across periodic table
First Ionization Energy
Energy needed to remove the first electron
Second Ionization Energy
Energy necessary to remove second electron from univalent cation (X+) to form divalent cation (X2+)
* Higher than first ionization energy
Electron Affinity
Energy dissipated by gas when it gains an electron
* Exothermic (expels heat)
Electronegativity
Measure of attractive force an atom will exert on an electron in a chemical bond
* Greater electronegativity, the more it attracts electrons
* Follows same pattern as ionization energy
Periodic table trends
Alkali Metals
- Group 1
- Lower density for metals
- Largest AR
- Easily lose an electron to form cations
- React easily with nonmetals ESPECIALLY halogens
Alkaline Earth Metals
- Group 2
- Slighlty higher Zeff and smaller AR
- Two electrons easily removed to form divalent cations
- Aren’t naturally found in neutral state
- Highly reactive to water
Chalcogens
- Group 16
- Nonmetals and metalloids
- Small AR and large IR
- At high concentrations are toxic/damaging
Halogens
- Group 17
- Highly reactive nonmetals
- Desperate to complete octet by gaining an electron
- Especially reactive to Alkali and Alkaline Earth Metals
- Found as ions (halides) or diatomic molecules
Noble Gases
- Group 18
- Inert gases because minimal reactivity since filled valence shells
- High ionization energy
- No electronegativity
Transition Metals
- Groups 3 - 12
- Metal
- Low electron affinities, low ionization energies, and low electronegativities
- High melting MP & BP
- Have different possible charged forms (oxidation states)
- Valence electrons increases as atomic number increases
