Ch.9 Atoms and Light (hw)
What a chemical symbol is
A chemical symbol is shorthand for the name of an element. It uniquely identifies the element. The chemical symbol may be either one or two letters. If the symbol is two letters, the first letter is capitalized and the second is lowercased.
Distinguish between atomic number and mass number.
Atomic number is the number of protons in the nucleus. Mass number is the total number of protons and neutrons in the nucleus.
The characteristics of metalloid
Metalloids can be induced to conduct electricity to a small extent and thus are known as semiconductors.
The characteristics of metals
Metals are generally solids at room temperature with the exception of mercury, which is liquid at room temperature. Metals have a lustrous (or shiny) appearance and are good conductors of heat and electricity.
The characteristics of nonmetals,
Nonmetals on the other hand are gases or pale, brittle, or soft solids that are bad conductors of heat and electricity.
If you place a Styrofoam cup on the table and a bunch of BBs move around it randomly, what will happen to the cup, and why?
The cup will move randomly in different directions because the BBs will exert unequal forces on the cup in different directions.
How elements are arranged in the periodic table
The elements are arranged in the periodic table according to their atomic numbers. The metals are arranged on the left side of the periodic table, the nonmetals are on the extreme right, and the metalloids are placed in between metals and nonmetals. The periodic table also tells us whether the substance is solid, liquid, or gaseous.
What is the relationship between the maximum number of electrons each shell can hold and the number of elements in each period of the periodic table?
The maximum number of electrons each shell can hold is equal to the number of elements in the corresponding period.
Why did the particles jiggle around?
The particles were struck by atoms, but unequally on different sides.
How do we account for the great variety of substances in the world?
There are many possible combinations of atoms.
Is there a limit to the number of electrons that can occupy a single shell?
Yes, because that's just the way it is.
What happens as we move from left to right across a period of the periodic table?
atomic size generally decreases.
What happens as we move from top to bottom down a group of the periodic table?
atoms size generally increases
Electromagnetic waves are composed of
electric and magnetic fields.
outside the nucleus
electrons
The atoms that make up your body
have existed since the start of the universe.
Neutron characteristics
no charge particle labeled "A"
Proton characteristics
particle labeled "B" approximately the same mass as a neutron +1 charge
Electron characteristics
particle labeled "C" -1 charge smallest mass of the three
Inside the nucleus
protons and neutrons
What did Robert Brown see under the microscope?
specks of dust moving around
