In 1911 _____________ found evidence that countered Thomson's model
Who is Ernest Rutherford
100
The modern model describes an atom as consisting of a __________ that contains protons and neutrons surronded by a cloud like region of moving electrons.
What is a nucleus.
100
By 1869 a total of __ elements had been discovered.
What is 63
100
The periodic table is organized in horizontal rows called ________
What is periods?
200
In 1897 a british scientist __________ found that atoms contain negatively charged particals.
Who is J.J. Thomson
200
________ dont affect the charge of an atom because they have no charge.
What is neutron
200
Mendeleev knew that some elements have similar ________ and physical properties.
What is chemical?
200
The elements of the modern periodic table fall into __ vertical columns.
What is 18
300
A danish scientist named ___________ and student of both Thomson and Ruthford revised the atomic model.
Who is Niels Bohrs?
300
Although __________ may balance protons charge for charge, they cannot compare when it comes to mass.
What is an electron?
300
Mendeleev found that the properties of elements __________.
What is repeated
300
The periodic table has one square for each _______.
What is element
400
An english chemist named _________ inferred that atoms had certain characteristics.
Who is John Dalton
400
In reality atoms are amazingly ______.
What is small?
400
In ____ Mendeleev published the first periodic table.
What is 1869
400
Most chemical symbols contain one or two _______
What is letters.
500
In Ruthfords model of an atom the atom was mostly __________
What is empty space?
500
Every atom of an element has the same numbers of _________.
What is protons
500
The word __________ means "in a regular repeated pattern.
What is periodic.
500
The last number in the square is the average ____________.