Ch. 2 The Periodic Table

Periodic Table

Period: rows (1-7)
Group: column (1-18)
Isotopes: atoms with differing number of neutrons; weighted average by abundance is listen on table

Subatomic Particles

Name	Symbol	Mass	Charge
Beta	$\ce{^0_{-1}\beta}$ or $\ce{^0_{-1}e}$	0	1-
Positron	$\ce{^0_{+1}\beta}$	0	1+
Alpha	$\ce{^4_2He}$ or $\ce{^4_2\alpha}$	4	2+
Proton	$\ce{^1_1H}$ or $\ce{^1_1p}$	1	1+
Neutron	$\ce{^1_0n}$	1	0

Mass Spectrometry

Graph of the relative abundances of different isotopes of elements or molar masses of compounds

Periodic Properties

Alkali Metals: Group 1 metals
Alkaline Earth Metals: Group 2 metals
Transition Metals: Group 3-12 metals
Metalloids: Along the staircase
Halogens: Group 17 elements
Noble Gases: Group 18 elements

Isoelectronic: same electron configuration (electronically identical)
$\ce{H2}$ , $\ce{O2}$ , $\ce{N2}$ , and halogens form diatomic molecules
Allotropes: different formations of elements with different properties

for example $\ce{O2}$ and $\ce{O3}$

Atomic Radii: size of the atom

trend for radii:

increases from top to bottom (more energy levels)
decreases from left to right (stronger effective nuclear charge)

Ionization Energy: energy needed to remove an electron

trends for first ionization energy:

decreases from top to bottom (weaker effective nuclear charge)
increases from left to right (stronger effective nuclear charge, electron repulsion might reduce)

Photoelectron Spectroscopy

Photoelectric Effect: high-energy beams trained on element surface, electrons can be ejected
$\text{Binding energy}=E_\text{incoming photon}-E_\text{emitted photoelectron}$

Peaks represent orbitals with 1s on the left

Electron Affinity: energy change accompanying addition of electron

negative if easily attracts electrons; releases energy
positive if difficult to accept; requires energy
high near fluorine, low near francium

Electronegativity: attraction of electrons by individual atoms

same trend as electron affinity