Chapter Nine- Parts Of The Atom Flashcards
What were John Daltons ideas?
Atoms cannot be divided, created or destroyed.
During a chemical reaction, atoms of an element cannot be converted into atoms of another element.
Atoms of one element are identical to each other but different from atoms of another element.
Atoms combine in specific ratios.
What did Democritus believe?
Atoms are small solid objects that cannot be created, divided or destroyed.
Atoms are constantly moving in empty space.
Different types of matter are made from different types of atoms.
The properties of the atoms determine the properties of matter
Who was Thomson?
Thomson found from his cathode ray experiment, that cathode Rays were made of small, negatively charged particles called Electrons
(Discovered electrons)
Who was Rutherford?
Rutherford concluded that most of an atoms mass and positive charge was is in a small, dense area in the center of an atom called the Nucleus.
What did Chadwick discover?
James Chadwick discovered that in addition to protons, the nucleus also contained neutrons
What did Bohr discover?
Agreed with what Rutherford said, except that Bohr said electrons moved in circular orbits and in the same orbit.
What is the current modern theory?
Research showed that energy levels are not arranged in circular orbits. Electrons form an electron cloud.
Atoms
Small particle that is the building block of matter; smallest piece of an element that still represents the element
Electron
A particle with one negative charge
Nucleus
Small area in the center of the atom where most of an atoms mass and positive charge is
Proton
An atomic particle that has one positive charge
Neutron
A neutral particle that exists in the nucleus of an atom
Electron cloud
An area around an atomic nucleus where an electron is most likely to be
(Modern theory)
atomic number
The number of protons in an atom of an element
Isotopes
Atoms of the same element that have different numbers of neutrons
Average mass of the elements isotopes, weighted according to the abundance of each isotope
Average atomic mass
Radioactive
Elements that spontaneously emit radiation
Nuclear Decay
Process that occurs when an unstable atomic nucleus changes into another more stable nucleus by emitting radiation
An atom that is no longer neutral because it gained or lost electrons
Ion
True or False: Neutrons have 2 down quarks and one up quark
True
True or False: Protons have two down quarks and two up quarks
False: Protons are made of 2 up quarks ONE down quark
Describe Electrons
Electrons: has one negative charge, means amber in Greek, most likely to be in an electron cloud, constantly move around the nucleus, impossible to know exact location, no smaller part, relative mass is 1/1,840, symbol: e-, equal to protons in an atom.
Describe neutrons
Quarks make up neutrons, they are neutral, symbol: n, location: nucleus, relative mass: 1, two neutrons are in an alpha particle, adding or removing neutrons from an atom doesn’t create a different element, discovered by James Chadwick.
How do you find the number of neutrons in an atom?
Mass number- Atomic number
Protons+ neutrons)-(number of protons
