Atoms Flashcards
What is an atom?
An atom is the smallest particle into which an element can be divided in and still be the same substance.
What is an element?
An element is the simplest pure substance.
What is a pure substance?
A pure substance is a substance that you can’t break down into other substances and still have the same chemical and physical properties.
About how many total elements are there?
There only about 118 elements. EVERY SINGLE substance on earth is made up of same combination of these elements.
How many atoms would it take to equal the thickness of a sheet of aluminum foil?
50,000!!!!
What is a nucleus?
It contains protons and neutrons.
What is a electron cloud?
It’s the area outside of the nucleus that holds the electrons.
Protons - the facts:
> subatomic particles
positively charged particles
All protons are exactly like all other protons (a proton from a gold atom is the same as a proton from a Nitrogen atom)
Neutrons - the facts:
> subatomic particles > Located inside the nucleus > all neutrons are exactly like all other neutrons > neutrons have NO electric charge > neutrons are neutral
Electrons - the facts:
> subatomic particles
located outside of the nucleus in the electron cloud
electrons are negatively charged
What are shells?
They are different levels of energy called shells, where electrons are believed to orbit around the outside of the nucleus of the atom in the electron cloud.
What can the number of protons determine?
It can determine what the element is.
How do you know the amount of protons each atom has?
Since each element has its own element key, you can tell by checking the atomic number, which indicates the number of protons.
How are the number of electrons and protons in an atom related?
In an atom, the number of electrons is the same as the number of protons.
What is the term for an “Atomic Mass Unit”?
AMU
What is the mass of one proton and one neutron?
The mass of one proton = 1 AMU
The mass of one neutron = 1 AMU
How do you find the mass of the atom?
Add up the Protons and Neutrons
Since electrons are so tiny, they don’t get counted inn the mass
How do you know the mass of an element?
Look at the mass number on the element key.
Where are electrons located in?
They are located in shells or energy levels.
Each sell can only hold a specific number of electrons 1st shell - \_\_\_ electrons 2nd shell -\_\_ electrons 3rd shell - \_\_\_ electrons 4th shell - \_\_\_\_ electrons
1st - 2
2nd - 8
3rd - 8
4th - 18
Electrons shells are filled up starting in the shell ______.
closest to the nucleus
Once that shell is full, then the ______ gets filled up and so on.
next shell
What are valence electrons?
They are the electrons in the outermost shell.
There can be no more than ___ valence electrons.
8
What is the exception?
The exception is H and He because they only have 1 or 2 electrons so they are full at 2.
Why are valence electrons important?
> They determine some of the chemical properties of the element
They are the only electros involved inn chemical reactions.
