History of the periodic table and atomic theory

What was Dmitri Mendeleev's greatest contribution to the history of the periodic table?

• He arranged all of the known elements by their atomic number
• He realised that there was a pattern of reactivity which repeated every 8 elements
• He predicted the existence (and properties) of new elements
• He identified the "law of triads" which became the groups

Why were there blank spaces left in Mendeleev's periodic table?                                              

• He didn't know what to put there.
•  Undiscovered elements not yet known.
• Multiple elements could have fit
• He forgot to add the elements in.

Which of these was not proposed by John Dalton in 1805?

• All matter is made of atoms
• Atoms are made of protons, neutrons and electrons
• During chemical reactions, atoms rearrange themselves
• The atoms of a particular element are all identical

Tags

NGSS.MS-PS1-5

Which of the following models of an atom is most widely accepted as correct?

• Bohr model
• Quantum-mechanical model
• Atomic model
• Radioactive model

Why did scientists need/want to organize the elements?

• Scientists like things organized
• make it easier to understand the elements
• have one list of the known elements.
• none of the above

What were the scientists looking for among the element properties to help them organize?

• boiling points

• chemical reactivity

• patterns among properties

• naming similarities

Mendeleev classified elements based on not only atomic mass but what else?                                                   

• reactivity
• boiling points
• physical properties only 
•  chemical & physical properties

Place the following scientists in order, from earliest to latest: 
A) Ernest Rutherford
B) J.J. Thomson
C) John Dalton

• B,C,A
• C,A,B
• A,C,B
• C,B,A

Tags

NGSS.MS-PS1-1

Rutherford's gold foil experiment provided evidence that...

• negative and positive charges are spread evenly throughout the atom.
• alpha particles have a positive charge.
• gold is not a dense as previously thought.
• there is a dense positively charged nucleus at the center of an atom.

Bohr's model of the atom proposed that ___.

• electrons move around the nucleus in fixed orbits
• neutrons move around the nucleus
• neutrons do not exist, but are just paired protons and electrons
• the nucleus spins