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Ch 2 RAD 150

The Structure of Matter

QuestionAnswer
During the Greek era, scientist believed that all matter was composed of what four substances? earth, water, air and fire
_____ elements have been identified. 118
An _____ is the smallest particle that has all the properties of an element. atom
According to Dalton, an element was composed of ______ atoms that reacted the same way chemically. identical
Mendeleev's work resulted in the: periodic table of elements
J.J Thompson described the atom as a ____ _____. plum pudding
In 1911, _______ described the atom as a dense, positive nucleus surrounded by a cloud of negative electrons. Rutherford
In 1913, ____ described the atom as a miniature solar system. Bohr
The center of an atom is termed the ____. nucleus
Name the three fundamental particles of an atom: neutron, proton and electron
Stable atoms are considered electrically _____. (same number of protons and neutrons) neutral
Because of its size, the atomic particle is expressed in _____. (amu) atomic mass unit
Atoms that have the same number of protons but differ in the number of neutrons are ______. isotopes
______ is the removal or addition of an orbital electron from an atom. Ionization
The _____ _____ distinguishes elements by number of protons contained in the nucleus. atomic number
Protons and neutrons are subdivided into _____ and _____. quarks; gluons
Protons and neutrons are located in the _____. nucleus
Electrons are located in ____ surrounding the nucleus. orbits.
The _____ an orbit is to the nucleus, the stronger the binding energy. closer
What is the max number of electrons that can exist in the O shell? 50 (use the 2n2 formula) (O is the 5th shell)
The formula 2n2 gives you the ____ number of electrons in a shell. maximum
Atoms of various elements combine to form _____; Molecules combine to form ______. molecules; compounds
The value ____ eV is called the ionization potential. 34
Chemical combining characteristics describes how an ____ will bond with other atoms. atom
Abbreviations of elements are called ____. chemical symbols
The number of protons is called the ______. atomic number
Atomic nuclei that have the same atomic mass number but different atomic numbers are ________. isobars
Atoms that have the same number of neutrons but different number of protons are _____. isotones
_____ have the same atomic number and the same atomic mass number. Isomers
In _____ emission, an electron is created and ejected from the nucleus of an isotope. beta
In _____ emission, an isotope emits 2 protons and 2 neutrons, changing chemically and in weight. alpha
The process of a nucleus spontaneously emitting particles and energy and transforming itself into another atom to reach stability is called _____ ____. radioactive decay
3.3 half lives = 1 tenth life
Particulate radiation is associated with ___ and ____ particles and radioactive decay. alpha, beta
The ____ particle range is longer than that for a _____ particle. beta; alpha
X-rays and gamma rays are forms of _______. electromagnetic ionizing radiation
X-rays and gamma rays are often called _____, which travel at the speed of light. photons