Topic 1 - Atoms, Molecules, Isotopes and Ions Flashcards
All the different substances in the world are made from fundamental materials called_______________
Elements
What is an element?
An element is a:
- substance
- which cannot be split into 2 or more simpler substances
- by chemical means.
How is every element unique?
Because every element has its own name and symbol.
Eg. Lithium = Li,
Magnesium = Mg
All elements are made of many small particles called:
ATOMS
In any one element, all the atoms are _______________.
The atoms of each element are unique because ___________________.
In any one element, all the atoms are identical to each other, but different from all other elements (in size and mass).
Each element has its own type of atoms.
Because the atoms of each element have a different size and mass from the other elements.
What is an Atom?
An atom is the SMALLEST particle of an element.
It has the symbol of the element.
How do you represent Atoms?
- Circles (different size and symbols)
- Ball and stick modles - spheres connected by sticks
How can you see an atom?
Using an electronic microscope.
What are the particles in an Atom?
Sub-atomic particles called:
- Protons;
- Neutrons; and
- Electrons
What do Protons and Neutrons make up?
The Nucleus of the Atom.
What is the symbol, charge and relative mass of a proton?
Symbol = p
Relative Electric Charge = +1
Relative mass = 1
What is the symbol, charge and relative mass of a Neutron?
Symbol = n
Relative Electric Charge = 0
Relative mass = 1
What is the symbol, charge and relative mass of an Electron?
Symbol = e
Relative Electric Charge = - 1
Relative mass = 1/1840
Every element has its own Atomic Number and Mass Number.
How do you indicate the Atomic Number and
Mass Number of an element?
What is an Mass Number of an element?
Mass Number =
Total Number of
Protons + Neutrons
What is the number of electrons in the
outermost valence shell
within each group of the Periodic Table?
What is a positive ion called?
A Positive Ion is called CATION (read cat-ion).
See example of Sodium and Magnesium atoms and cations:
How is Sodium ion formed from Sodium atom?
How is Magnesium ion formed from Magnesium atom?
Sodium atom (2:8:1) loses 1 electron (1e) to form Sodium ion (2:8)
Na - 1e = Na+
Magnesium atom (2:8:2) loses 2 electrons (2 e) to form Magnesium ion (2:8)
Mg - 2e = Mg2+
See example of Chlorine and Oxygen atoms and cations:
How is Chlorine ion formed from Chlorine atom?
How is Oxygen ion formed from Oxygen atom?
Chlorine atom (2:8:7) gains 1 electron (1e) to form chloride ion (2:8:8)
Cl + 1e = Cl-
Oxygen atom (2:6) gains 2 electrons (2 e) to form Oxygen ion (2:8)
O + 2e = O2-
What are the similarities and differences between Isotopes?
Similarities:
- Similar Atomic Number (since proton # same)
- Similar number of protons;
- Similar number of electrons (since p # = e #)
- Similar chemical properties
Differences:
- Different number of neutrons;
- Hence different mass number (since Mass # = p + n);
- Different physical properties (eg diffusion rate, density, mass, etc.)
Working example of Hydrogen/ Deuterium/ Tritium:
Atomic # =
Number of p =
Mass # =
Number of n =
Hydrogen:
Atomic # =
Number of p =
Mass # =
Number of n =
Deuterium:
Atomic # =
Number of p =
Mass # =
Number of n =
Tritium:
Atomic # =
Number of p =
Mass # =
Number of n =
What is a molecule?
A Molecule is a group of 2 or more atoms chemically joined together.
What is a diatomic molecule?
What are common examples?
Diatomic molecules are simple molecules made of 2 atoms chemically joined together.
Most non-metallic elements consist of diatomic molecules.
What is the difference between the molecules of an element v
the molecules of a compound?
Molecules of element: consist of fixed number of 1 kind of atoms
Molecules of compounds: consists of a fixed number of 2 or more different kinds of atoms
