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10 questions
Before Mendeleev's table, how were elements arranged in order to classify them?
In order of atomic mass
In order of atomic weight
By physical and chemical properties
They weren't
What were some problems with the early versions of the periodic table?
Some elements had not been discovered so the tables were not complete.
The elements did not follow a regular pattern.
The weight of some elements had been calculated incorrectly.
Elements were placed in order of atomic weight, so some ended up in the wrong group.
In the periodic table, the ______ number tells us the number of electron shells in an atom.
How did Mendeleev overcome some of the problems in his version of the periodic table?
He made up new elements to fill in gaps.
He left gaps for undiscovered elements.
He ordered the elements in terms of atomic mass.
He placed elements in groups according to similar properties.
Placing the elements in order of atomic weight was incorrect because some elements have ________ that have different masses.
In the periodic table, the _____ number tells us the number of electrons in the outer shell of an atom.
Bromine is in Group 7. How many electrons are in the outer shell of a bromine atom?
An atom of sodium has 3 electron shells. What does this tell us about the atom?
It is in Group 3 of the periodic table
It is in Period 3 of the periodic table
It has 3 electrons
Molecules of sodium contain 3 atoms
Magnesium is in Group 3 and Period 2. What is the electronic structure of magnesium?
1.1.1
3.2
2.8.2
2.8.8
An element is in Group 6 and Period 3. How many electrons does it have in total?
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