History of atomic models and structure of the atom
positively charged subatomic particle with mass of 1u. Located in the nucleus.
negatively charged subatomic particle with mass of 1/1840 u. Located outside the nucleus in orbitals.
neutral subatomic particle with mass of 1 u. Located in the nucleus.
the smallest particle of an element.
the dense, center of an atom. has a positive charge. made up of protons and neutrons.
particles that are smaller than an atom
the difference in the positive charge due to protons and the negative charge due to electrons.
the number of protons in an atom. Determines the identity of the element.
the total number of protons and neutrons.
atoms with the same number of protons, but different number of neutrons and a different mass number.
average atomic mass
the weighted average of all the isotopes that are present in an element.
Greek philospher that originiated the idea of the atom (atomos). Matter is made up of tiny indivisible particles.
Matter is made up of particles called atoms. Atoms of identical elements are all identical. Atoms combine in whole number ratios to form compounds. Atoms are rearraged during a chemical reaction but no new atoms are created.
Plum Pudding Model. Atoms consist of electrons in a "pudding" of positive charge. Experiment with cathode ray tube found that atoms contain negatively charged particles called electrons.
Gold foil experiment. Atoms are mostly empty space with a small, dense positively charged nucleus.
electrons exist in circular orbits of specified energy around the nucleus.