Periodic Table
What are metalloids?
Characteristics of metals and non-metals, Brittle solids with metallic luster, semiconductor.
What are neutrons?
A subatomic particle found in the nucleus with no electrical charge. It is the most massive of the three subatomic particles.
What is atomic number and how is it represented?
The number of protons in the nucleus of an atom, it's represented as a whole number.
Who thought atoms were indivisible?
Democritus (Greek scientists)
How did the modern periodic table come to be?
scientists attempting to arrange the elements, recognizing the periodic nature of elements and trying to organize elements based on the structure of their atoms.
What are metals?
Few valence electrons. Ductile, malleable, lustrous, solid, highly conductive and reactive. This group includes the majority of the elements.
What are protons?
A subatomic particle found in the nucleus with a positive charge and this also determines the atom's identity.
What is mass number and how is it represented?
The total number of protons and neutrons, it's represented as a whole number.
Who developed the nuclear model?
Ernest Rutherford
How are the elements on the periodic table arranged?
By the atomic numbers
What are nonmetals?
Four or more valence electrons, gas, liquid, dull, brittle, poor conductors
What are electrons?
A subatomic particle found outside of the nucleus with a negative charge and is the smallest of the three subatomic particles.
What is atomic mass?
The approximate number of protons and neutrons (their average), it's usually represented as a decimal.
Who developed the plum pudding model?
J.J. Thompson
What do the columns of the periodic table represent and what are they called?
They are called families or groups and represent elements with the same number of valence electrons.
Who demonstrated that combustion requires oxygen and therefore, fire is not an element?
Antoine Lavoisier
What is the law of electrostatic charges?
Opposite electric charges attract, like electrical charges repel.
Describe how electrons move around the nucleus according to Bohr's model.
Electrons travel in distinct, spherical orbits around the nucleus.
Who believed electrons move through spherical regions at a fixed distance from the nucleus and created the atomic model we use today?
Niels Bohr
What do the rows on the period table represent and what are they called?
They are called periods and they represents the energy level of the valence electrons.
Who led to the reorganization of the periodic table based on atomic number?
Henry Moseley
Why is the Bohr model of the atom still used today, even though it isn't complete?
It is easy to understand, represents energy levels in a visual way, and is useful for showing how chemical bonding works.
What five elements did the Greeks think all matter in the universe was made of?
Fire, water, air, earth, and aether
Who believed elements are made of atoms that are all alike?
John Dalton
What letters are used to represent elements?
Always at least one capital letter, often followed by a lower case letter.