Atoms & Radioactivity Flashcards
5 signs of chemical change
Change in color, smell, precipitate, release of energy (heat or light), and bubbles.
6 metalloids
Boron, silicon, geranium, antimony, arsenic, and tellurium, forms a staircase pattern on the periodic table.
fission
when the nucleus gets deformed and the electrical force overcomes the nuclear force and two more stable atoms are formed, occurs spontaneously. Can be induced by bombarding the nucleus with neutrons. Example- U-238 and U-235 (explosion)
fusion
Two light nuclei come together to create one large nucleus. Requires VERY high temperatures. Has no radioactive waste.
Symbol, charge, and what stops alpha radiation
Little fishy symbol and 4/2 He (helium nucleus), 2+ charge, and skin or paper stops it.
Symbol, charge, and what stops beta radiation
B with a long tail symbol and 0/-1 e (electron), 1- charge, and is stopped by aluminum foil or plastic.
Symbol, charge, and what stops gamma radiation
Y with a loopy tail symbol, it is jsut pure energy so there is no equation (happens when excited atoms readjust), and it is stopped by thick lead.
critical mass
The amount of fissionable material it takes to get a chain reaction going.
plutonium
Can be used besides Uranium to make nuclear power or power plant fuel.
half life
The amount of time it takes for a radioactive substance to decay.
alchemists
Alchemists led to the scientific method, but not to the ability of turning lead into gold.
Georg Stahl
All flammables contain phlogistan (Greek for “set on fire”), and it allows it to burn. Burning causes the loss of phlogistan. Ashes can’t burn because its all gone. Substances should lose mass when they burn if phlogistan is lost.
Law of Conservation of Mass
Mass isn’t created or destroyed during chemical or physical reactions, and what goes in must come out.
What led to the Law of Conservation of Mass, Law of Definite Proportions, and the Law of Multiple Proportions?
Development of accurate balances in the 1700s.
Law of Definite Proportions
A chemical compound has the same element in the same proportions no matter the sample size.
Law of Multiple Proportions
If there are two different compounds composed of the same elements, the ratio of mass and number of atoms will be a whole number.
Dalton’s Atomic Theory
- All matter is composed of extremely small particles called atoms.
- Atoms in a given element are identical; different elements differ.
- Atoms can’t be subdivided (NOT true), created, or destroyed.
- Atoms of different elements combine in simple whole number ratios to form chemical compounds.
- In chemical reactions, atoms can be combined, rearranged, or separated, but not changed.
JJ Thompson
Created cathode ray tubes that contained gases at low pressure in glass tubes and passed electrical currents through them. Anode has a positive charge and cathodes have a negative charge. The ray attracted towards positively charged metal plates and repelled by negatively charged plates.
Millikan
Determined the mass of an electron to be 1/1,840 of a proton.
Goldstein
Used the metallic plates and the cathode ray on Hlittle2 without the electrons and discovered there was a positive charge left.
Chadwick
Confirmed the presence of a neutron. Created the plum pudding model, with the electrons incorrectly stuck in the lump of positively charged protons.
Rutherford
Created the gold foil experiment. He expected that the alpha particles would not pass through and they would be mildly deflected. The actual result is that most alpha particles passed straight through without deflection, but a few bounced off at large angles. Proved that the vast majority of particles must be empty space.
isotopes
Atoms of the same element with different masses. They have a different number of neutrons but the same number of protons. They are chemically similar with different physical properties.
Avogadro
Found the number of particles in exactly one mole of a pure substance.
