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Chapter 4

Atomic Structure

QuestionAnswer
What did Democritus call natures best particle of an atom? indivisible and indestructible
Who was the english chemist and teacher that formulated theory to describe structure and chemical reactively of matter in an atom? John Dalton
What is an atom? elements composed of tiny particles that retains its identity in a chemical reaction
In what type of ratios do atoms combine to form compounds? Atoms of different elements can physically mix together or chemically combine in simple whole-number ratios
Who was the Greek philosopher among the first to suggest the existence of atoms? Democritus
What does John Dalton's Modern Atomic Theory state? atoms are divisible and an element can have atoms with different masses
What did John Dalton propose? elements were composed of atoms and only whole-number of atoms can combine to form compounds
Why can Dalton's ideas be called a theory? He changed Democritus' ideas into a theory that could be tested.
What is the nucleus? the central core of an atom
Which subatomic particles are in the nucleus of an atom? protons and neutrons
What are the three subatomic particles? protons, neutrons, and electrons
What was Rutherford's atomic model? "nuclear atom"
Who discovered the neutron (other component of the nucleus) in 1932? James Chadwick
Which subatomic particle occupies most of the volume of the atom? Electron
What is a cathode ray? stream of electrons produced at the negative electrode of a tube containing a gas at low pressure
What did Democritus believe about atoms? they physically resembled the matter it made (rock atoms were sharp and jagged, fur atoms were soft and fuzzy)
What do the "anatomy" af an atom have? a nucleus and electron could
Who discovered the electron? J.J. Thomson
How did J.J. Thomson know the ray was composed of negatively charged particles? the particles deflected by a magnetic field in the same way as a wire carrying an electrical current
What does the presence of a negatively charged particle within a neutral structure (atom) have a indication of? negatively charged particles moving up the cathode ray
What does the very small mass of the electron compared to the relatively large mass of an atom indicate? there is probably a positively charged particle in the atom that has more mass than the electron
What is Thomson's atomic model? 'plum pudding'
When Ernest fired the alpha particles through a thin piece of gold foil, what did he expect the particles to do? deflect
What actually happened with the most of the alpha particles? they went straight through the gold foil undeflected
What actually happened with the other alpha particles? some: were deflected few: bounced back at large angles
Why could Rutherford conclude that the atom is mostly empty space? some alpha particles went through
Why could Rutherford conclude that there was a small, dense, area of positive charge? some particles were deflected
What did Thomson detect that the electron has? a certain amount of negative charge per unit of mass
What does Thomson's 'Plum Pudding' not have? a nucleus and neutrons
What is the atomic number? # of p+ and e- in each atom of that element
How are elements different from one another? they have different #s of protons
What is the mass number? total # of p+ and neutrons in nucleus.
What is the atomic mass? weighted average mass of the atoms in a naturally occurring sample of an element
How do you find the # of neutrons? atomic number - atomic mass (rounded)
If the atom is neutral (no charge) then what does it have? the same # of e-
What are neutrons? subatomic particle that has no charge but has a mass nearly equal to that of a proton
What are electrons? subatomic particle that are negatively charged
What are protons? subatomic particle that is positively charged
What does I amu equal? 1/12 the mass of a carbon-12 atom
What would you do to calculate atomic mass? 1. Multiply the mass of each isotope by its % natural abundance (in decimal form, rounded 2 to the left) 2. Add the answers
What are atoms of the same element that have different masses (different amounts of neutrons)? isotopes
How is (nuclear notation) expressed? mass # on top, element, atomic # on bottom
How is hyphen notation expressed? element-# #of p+ and neutrons
What is a periodic table? an arrangement of element where the elements are separated into groups based on a set of repeated properties
What is a group? each vertical column in the periodic table
What is a period? each horizontal row of the periodic table
Created by: dwigmans13