Chap 11

• Atom - basic unit of matter
• John Dalton - proposed the atomic theory which explained the laws of chemical change
• Atom - smallest component of matter
• William Crookes - conducted experiments using gas discharge tube.
• cathode rays - negatively charged streams or rays
• J.J

  Thomson - discovered electrons
• Robert Milikan - determined the charge of electrons
• Eugen Goldstein - studied cathode rays
• positive rays - positivity chargeed
• Proton - positive particles
• nucleus - positively charged center of atom
• Neutron - uncharged particles
• James Chadwick - identified these uncharged particles
• Atomic number - corresponds to the number of protons in a atom.
• Mass number - corresponds to the total number of nucleos in a atom
• Nucleons - the protons and neutrons in the nucleus
• Isotopes - atoms of the same element with the same atomic number but different mass number
• Mass spectrometry (MS) - the most direct and most accurate method of determining the atomic mass and molecular mass.
• The nucleus of an atom is composed of protons and neutrons.
• Electrons and protons are charged particles, while neutrons are uncharged.
• A neutral atom is one where the number of protons equals the number of electrons.
• The atoms of an element always have the same number of protons.
• Isotopes have the same number of protons but different number of neutrons.
• Dalton's atomic theory postulate that all atoms of all forms of matter are the same is not true.
• J.J Thomson proposed that electrons are embedded in a positively charged sphere or cloud.
• In a potassium atom, the number of electrons, protons, and neutrons, respectively, are 19, 19, 20.
• The mass number of the potassium atom in item 8 is 39.
• The atomic number serves as the identity of an element.
• Ernest Rutherford discovered protons.
• James Chadwick discovered neutrons.
• John Dalton developed the atomic theory of matter.
• J.J Thomson discovered electrons.
• Robert Milikan determined the charge of electrons.