Chapter 8: Atoms and Molecules Electronic Configuration and Isotopes Flashcards
Define ‘atom’
It is the simplest unit of an element.
What are the 3 subatomic particles?
Protons, neutrons and electrons
What are the relative masses of the subatomic particles?
Protons: 1u
Neutrons: 1u
Electrons: negligible (or 1/1836)
In the periodic table, which number represents the amount of protons in that element?
Top number
In the periodic table, which number represents the number of neutrons + protons in that element?
Bottom number
What is the ‘top number’ of an element known as?
Proton/ Atomic number
What is the ‘bottom number’ known as?
Mass/ Nucleon number
How are the elements in the periodic table arranged?
They are arranged in ascending order of proton number.
Why are atoms electrically neutral?
The number of negatively charged neutrons are equal to the number of positively charged protons. Thus they cancel out each other.
What is a characteristic of an ion?
The number of electrons and the number of protons are not equal.
How many electrons can each electron shell take?
1st shell: 2
2nd shell onwards: 8
How do you find out how many electron shells there are?
You can look at the element’s period number.
What does ‘valence’ mean?
Outermost.
What does the number of valence electrons tell you about an element?
Its group number, chemical reactivity
What is so special about Group 18 of the periodic table?
They are noble gases, meaning that they are non-reactive.
Why are the elements in Group 18 non-reactive?
They have a fully filled valence shell, meaning that they do not need to lose or gain electrons ; they are stable.
Define ‘isotopes’
Isotopes are atoms of the same element with the same number of protons but different number of neutrons.
What are the characteristics of isotopes?
- They have the same chemical properties
- They have different physical properties (e.g. boiling point, density)
Define ‘molecule’.
It is a substance formed when two or more atoms are chemically combined (reaction) together.
What is the characteristic of a molecule of an element?
The molecules are made up of the same type of atoms.
What is the characteristic of a molecule of a compound?
The molecules are made up of different types of atoms.
Can Group 18 elements form a molecule? Why?
No, since they are unreactive, they are unable to react with any other atoms to form a molecule, thus they will always exist as an atom.
What do you need to do if you have 3 or more valence shells and the number of valence electrons are more than 3?
You have to add 10 to the number of valence electrons to get the group number of that element.
