How did Democritus characterize atoms?
Democritus believed that atoms were invisible and indestructible
How did Dalton advance the atomic philosophy proposed by Democritus?
Dalton advanced atomic philosophy by using experimental methods
What instrument can be used to observe individual atoms?
Atoms can be observed using scanning tunneling microscopes
In your own words, state the main ideas of Dalton's atomic theory?
Dalton's atomic theory: atom's are very very small and make up everything in the natural world
According to Dalton's theory, is it possible to convert atoms of one element into atoms of another?Explain.
No, it's not possible to change the atoms into a different element because....
Describe the range of the radii of most atoms in nanometers(nm).
Most atoms radii fall with in the range of 10^-2
A sample of copper with a mass of 63.5 grams contains 6.02 X 10^23 atoms. Calculate the mass of a single copper atom.
9.5 X 10^-21 or 1.05 X 10^-22
What are three types of subatomic particles?
Protons, Neutrons, and Electrons
How does the Rutherford model describe the structure of atoms?
describes the atom as having a small, dense nucleus in which all the positive charge is gathered and a large area of empty space
What are the charges and relative masses of the three main subatomic particles?
Electron:1/1840
Proton: 1
Neutron:1
Describe Thomson's and Millikan's contributions to atomic theory.
Thomson: first person to suggest the theory of the atom containing positive and negative particles and demonstrated the latter which are called "electrons"
Millikan: discovered that the weight of an electron is 1840 times smaller than a hydrogen atom(atom
Compare Rutherford's expected outcome of the gold-foil experiment with the actual outcome.
Rutherford thought "Thomson MOdel" was correct and the initial results supported this interoperation. took him 2 years
What experimental evidence led to Rutherford to conclude that an atom is mostly empty space?
because most of the particles weren't "deflected off" of the gold-foil in his experiment
How did Rutherford's model of the atom differ from Thomson's?
Thomson: thought the protons and electrons were both distributed as a mixture with in a sphere
Rutherford: thought only protons formed a spherical core or nucleus and the electrons were outside the nucleus, in the orbit around it
What distinguishes the atoms of one element from the atoms of another?
the number of protons in an atom
What equation tells you how to calculate the number of neutrons in an atom?
atomic mass-atomic number
How do the isotopes of a given element differ from one another?
Isotopes are of the same element and they have the same number of protons; difference is that they differ in neutron number
How is atomic mass calculated?
multiply the mass of each isotope by its natural abundance,expressed as a decimal, and then add the products.
What makes the periodic table such a useful tool?
allows you to compare the properties of one element
What does the number represent in the isotope name "platinum-194"? Write the symbol for this atom using superscripts and subscripts.
-194; Platinum:78
194-78=116
The atomic masses of elements are generally not whole numbers. Explain why.
Atomic mass is the average of all the isotopes of that element that exist.
What is an atom?
Atom-makes up all things in the natural world
What were the limitations of Democritus's ideas about atoms?
atoms make up everything and are smaller than the eye can see
Use Dalton's atomic theory to describe how atoms interact during a chemical reaction
Dalton; in a chemical reaction atoms of an element are never changed into atoms of another element
What experimental evidence did Thomson have for each statement?
a) Electrons have a negative charge
b) Atoms of all elements contain electrons
Thomson experiment evidence:
a) electrons; charge in the calorays would bend away
b) atoms have electrons
How do the charge and mass of a neutron compare to the charge and mass of a proton?
Neutron=no mass
Proton= mass of atom
Why does it make sense that if an atom loses electrons, it is left with a positive charge?
The Electrons even out with the protons turns into negative charge.
Describe the location of the electrons in Thomson's "plum pudding" model of the atom.
The electrons were stuck in a lump of positive charge
How did the results of Rutherford's gold-foil experiment differ from his expectation?
Didn't think there was mostly empty space