Chapter 4 : Models of the Atom Flashcards
when was the concept of the atom “born”
450 B.C.
what Greek philosopher argued matter is discontinuous and could not be infinitely divided?
Democritus
in 350 B.C. who argued matter and motion are continuous
Aristotle
In 1803 who argued Aristotle’s proposal and claimed matter as discontinuous and offered experimental evidence to his claim (which Aristotle did not)
John Dalton
what are the five parts to the atomic theory
- an element is compose of tiny, indivisible, indestructible particles called atoms
- all atoms of an element are identical and have the same properties
- atoms of different elements combine to form compounds
- compounds contain atoms in small whole number ratios
- atoms can combine in more than one ratio to form different compounds
Define: electron
a negatively charged subatomic particle having a tiny mass
Define: proton
a positively charged subatomic particle with a mass of 1 amu
in 1903 who proposed a subatomic model of the atom which pictured a positively charged atom containing negatively charged electrons?
JJ Thomson
who coined the terms alpha ray, beta ray, and gamma ray. and found that alpha rays contained particles identical to those of helium atoms stripped of electrons
Rutherford
Define: atomic nucleus
a region of very high density in the center of the atom that contains protons and neutrons
What is: powerful alpha particles should pass through a homogeneous plum pudding gold atom. Because positively charged alpha particles are deflected, Rutherford reasoned correctly that a gold atom has a dense, positively charged nucleus
Alpha-Scattering
where is most of the mass of an atom found
the nucleus
Define: neutron
a neutral subatomic particle with a mass of 1 amu which is approximately equal to the mass of a proton
what is the location, relative charge, and relative mass of an electron
Location: outside the nucleus
Relative charge: -1
Relative mass: 1/1836
what is the location, relative charge, and relative mass of a proton
Location: inside nucleus
Relative charge: +1
Relative mass: 1
what is the location, relative charge, and relative mas of a neutron
Location: inside nucleus
Relative charge: 0
Relative mass: 1
Define: atomic number
a number that identifies a specific element . a value that indicates the number of protons in the nucleus of an atom
Define: atomic notation
a symbolic method for expressing the composition of an atomic nucleus; the mass number and atomic number are indicated to the left of the chemical symbol for the element
Define: mass number
A value that indicates the number of protons and neutrons in the nucleus of a given atom
Define: isotopes
atoms of the same element that have a different number of neutrons in the nucleus
as the number of neutrons vary, so does the mass
how do you refer to an isotope
state the name of the element followed by its mass number
