parts of an atom

Question Answer
What does atomos mean? uncuttable
What idea did Greek philosopher Democritus' propose? matter is formed of small pieces that could not be cut into smaller parts
Dalton's ideas? element composed of atoms cannot be divided, atoms of the same element are exactly alike, atoms cannot be created or destroyed in chemical change–only rearranged, every compound is composed of atoms of different elements-combined in specific ratio p.103
Thomson's main discovery? Atoms have negative particles (blueberry muffin)
What is an electron and its location in Thomson's model? negatively charged subatomic particle scattered throughout a ball of positive charges
What is a proton and its location? positively charged subatomic particle in the nucleus
What is a nucleus? center of the atom that contains protons and neutrons
Chadwick's discovery? a particle called a neutron that is neutral
How does the mass of a proton compare to the mass of a neutron? almost equal to each other
How much mass does an electron have? Almost no mass
What makes up most of the mass of an atom? proton and neutron
Define atomic number number protons are in an atom
Define isotope atoms of the same element that have the same number of protons and DIFFERENT numbers of neutrons
Main discovery in Rutherford's model? positive charge is contained in nucleus; atom was mostly empty space with electrons moving around the nucleus in that space
Why didn't ancient Greeks orive the existence of atoms? they didn't do experiments to test the hypothesis
How did the atomic theory begin to grow? people were able to do experiments, atomic models developed from experimental evidence. As more evidence was collected, models and theories were revised
Be able to explain in your own words Rutherford's gold foil experiment. p. 104 forced positively charged particles at a sheet of gold foil. most particles passed thru but some didn't go thru
What did Bohr's model show? electrons could have only specific amounts of energy, leading them to move in certain orbits; electrons orbiting the nucleus similar to planets orbiting the sun
example of visual model electron cloud
energy level electron's movement related to this. electron's of different energy levels are likely to be found in different places
Modern model of an atom p. 106 nucleus with protons/neutrons surrounded by cloudlike moving electrons; electrons located in cloudlike region surrounding nucleus
Protons positive charge
Electrons negative charge; no mass, has about 2000 times less mass than a proton; therefore, the mass of the atom is mostly made up of the mass of the protons and neutrons
Neutrons no charge
Proton and Electron EQUAL mass
mass number number of protons + neutrons
What is the difference b/t mass number and atomic mass? mass number is a whole number, found by rounding the atomic mass. Atomic mass is the AVERAGE mass of an atom of a particular element taking into account all the isotopes of the element
Dalton's atomic theory still accepted today w/only a few changes, all elements composed of atoms, atom of one element cannot be changed into atom of different element, atoms cannot be created or destroyed in any chemical change
Describe atoms most of the mass of an atom is due to its protons and neutrons, atoms have no overall electrical charge,
Why an atom is neutral atom has a certain number of positively charged protons in its nucleus, the atom has the same number of negatively charged particles in the electron cloud, the charges cancel out so atoms remain neutral
element can be identified by the number of PROTONS in the nucleus of its atoms
atomic number number of PROTONS, used to distinguish one element from another because the number of protons is unique for atoms of each element
3 main particles in the modern model of an atom proton, neutron, and electron
Why do atoms have no electric charge even though most of their particles have charges? atoms have no electric charge even though most of their particles have a charge because they have the same number of positive charges (in the protons) as negative charges (in the electrons) so the charges cancel each other
REVIEW THE ATOMS FAMILY: ATOMIC MATH CHALLENGE, study chart in back of the book, practice…. example: Oxygen Symbol: O, Atomic #: 8, Mass #: 16 (protons + neutrons), # of protons: 8, # of neutrons: 8, # of electrons: 8
Review ALL worksheets, class notes, reread textbook pages, and moodle!!!

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