Quiz 2 Flashcards
The number of protons in an atom is equal to the number of ___
electrons
Who first characterized the electron?
J.J. Thomson
Where are electrons located in an atom?
electron cloud
Who first characterized the neutron?
James Chadwick
Who first characterized the nucleus of an atom?
Ernest Rutherford
Why does the nucleus of every atom have an overall positive charge?
protons have positive charge and neutrons are neutral
Why is almost all of the mass of an atom located in the nucleus?
protons and neutrons are 1837 and 1839 times heavier than electrons
What is a nucleon?
any subatomic particle found in the nucleus of an atom
Protons have a mass slightly _____ than a neutron.
less
The ____ is the most massive of all the particles
neutron
What does “charge neutrality” refer to?
the fact that atoms are electrically neutral
What are isotopes?
atoms of the same element that have the same number of protons and electrons, but different numbers of neutrons
What is the relationship between the atomic numbers and mass numbers of two atoms that are
isotopes of the same element?
Atoms of the same element will have the same number of protons and thus the same atomic
numbers. However, since isotopes of the same element have different numbers of neutrons, they
will have different mass numbers.
What does the atomic number refer to?
number of protons in the nucleus of an atom (also electrons since there are the same amount)
What does the mass number refer to?
total number of protons and neutrons in nucleus
Why do atoms that are isotopes of the same element usually have the same chemical behavior?
The chemical behavior of isotopes is usually the same because it is the electrons in the atom that
determine its chemical behavior and not the protons or neutrons.
Atoms that are isotopes of the same element can have slightly different physical properties. Why is this?
Some physical properties, such as density, depend on the mass of the atoms that make up the
substance.
How did the work of Henry Moseley change the way chemical elements were organized on the periodic table?
His work with X – rays showed that the elements should be listed in order of atomic number
rather than their atomic weights because his work revealed that the atomic number was actually
reflected in a physical property of every atom and that there was a steady increase in this property
What property of an atom determines its identity as an element?
the number of protons in its nucleus
How can the atomic number and mass number of an atom be used to determine the subatomic
particle inventory of that atom?
The atomic number can be used to indicate the number of protons present in the atom. (and electrons)
The number of neutrons in an atom can be determined by subtracting the number of protons
(described by the atomic number) from the total number of particles in the nucleus (the mass
number).
What’s an isobar?
an atom that has the same mass number but different atomic number
What did Leucippus contribute to the atomic model?
water is the universal element
What did Democritus contribute to the atomic model?
air is the universal element
What did Antoine Lavosier contribute to the atomic model?
Law of Conservation of Mass
What did Joseph Louis Proust contribute to the atomic model?
Law of Definite Proportions
What did John Dalton contribute to the atomic model?
reintroduced atomic theory
Law of Multiple Proportions
What did JJ Thomson contribute to the atomic model?
electrons
sphere model proposed by John Dalton is wrong
What did Ernest Rutherford contribute to the atomic model?
nucleus
What did Neils Bohr contribute to the atomic model?
electrons travel around nucleus in orbits
What did Louis de Brogile contribute to the atomic model?
all matter has a wave characteristic
What did Erwin Schrodinger contribute to the atomic model?
doesn’t look like solar system
