Atomic structure and stability Flashcards
What is the Bohr model
Electrons orbit the positive nucleus at set distances away
Ion
charged atoms
what do atoms that want to become stable do
lose or gain electrons
Valence electrons
Electrons on the second electron shell
Anion
Type of ion with more electrons than protons (negative ion)
Cation
Type of ion with more protons than electrons (positive ion)
radio active decay occurs with release of
protons and/or neutrons
What did JJ Thompson do
discovered electron. plum pudding model. electrons are negatively charged embedded in a sphere of positive charge
What did Ernest Rutherford do
proved the plum pudding model wrong by firing positively charged alpha particles at thin pieces of gold foil. This discovered the nucleus, which has a positive charge.
What did Niels Bohr do?
Discovered the energy levels. He discovered that electrons orbit the nucleus in shells at set distances from the nucleus, creating the planetary model. Calculated this by observing light being emitted by heated atoms. (1913)
James Chadwick
Discovered the neutron
1/2 lives
amount of time it takes for one half of sample to decay
NA+ (what ion)
cation
F- (what ion)
anion
Why are some isotopes radio isotopes
because they have an unstable nuclei, causing them to undergo radio activity
alpha decay
release of an alpha particle. Has highest ionising strength and weakest penetration
Beta decay
Neutron turns into a proton, and an electron is expelled. moderate penetration and ionising
Gamma decay
energy is released as gamma rays. high penetration, low ironising.
