Periodic table test Flashcards
Johann Dobereiner (1817)
organized elements in triads(groups of three with similar properties)
John Newlands (1863)
Law of Octaves: when arranged by increasing atomic mass, elements properties are similar every eight element
Henry Mosely
Modern Periodic Law: of elements for repeating pattern when arranged by Atomic Number
Octet Rule
Atoms want to have full Valence shells (8 valence electrons)
Positive Ions
Cations
Negative Ions
Anions
Hydrogen can react in four way
- as a metal by losing electrons: forms positive hydrogen ion
- as a non-metal by gaining an electron this forms a negative hydride ion
- share electrons reacts this way with non metals
- hydrogen bonding forms bridges between two molecules
Allotropes
Different forms of the same element
Catenation
Carbon shares electrons with other carbon atoms to create long chains of polymers
Effective nuclear charge
amount of nuclear charge the electrons experience
Shielding effect
electrons further from the nucleus are screened by others and do not experience as much nuclear charge
Atomic Radius(size of atom) decreases as you move right across the periodic table why
because adding protons increase effective nuclear charge pulling electrons in towards Nucleus’s
Atomic radius (size of atom) increases as you move top to bottom why
because more shells(energy levels)
Positive ions
form when an atom looses electrons (metals)
Smaller then parent
Negative ions
form when an atom gains an electron (non-metals)
Bigger then parent
Ionization energy
amount of energy needed to remove an electron to create an ion
first ionization energy
energy needed to remove the most loosely held electron
ionization energy increases as you move left to right why
because electrons closer to nucleus (smaller atoms)
ionization energy decreases as you go top to bottom why
because electrons are further from the nucleus (bigger atoms)
Electron Affinity
attraction of an atom for an electron
Metals
Non-Metals
low electron affinity
high electron affinity (bond by gaining electrons)
reactivity of metals
when metal looses electrons there is a chemical reaction
L –> R metals get lest reactive
Top –> Bottom metals get more reactive
why
because metals react by losing electrons Big atoms with low ionization energy react easily
Reactivity if non-metals
when non-metals gain electrons there is a chemical reaction
Most reactive non-metal
Fluorine (the closer to fluorine the more reactive the non-metal)
why
non-metals react by gaining electrons small atoms can easily pull in electrons from other atoms
Stability rule
atoms with a full or half full sublevel is stable
Halogens
bond to each other to form diatomic compunds
diatomic compounds
are compounds of two identical atoms
