The Periodic table Flashcards
Isotopes
Where the atoms have different masses but the same proton and electron value- a different number of neutrons!
Covalent bonding
Where a pair of electrons is shared between two atoms.
There is a strong attraction between the bonding pair of electrons and nuclei of atoms involved
Giant covalent structures
- Made of millions of atoms bonded together to form a giant structure like diamond, graphite or silicon dioxide.
- They have very high melting points because so many strong covalent bonds have to be broken
Diamond
Used for cutting and jewellery because its hard and abrasive, there are no weak forces in this structure.
Graphite
Used as a lubricant- covalent bonds are strong but the forces of attraction between layers are weak.
Ionic (electrovalent) bonding
Where the electrons are shared between two atoms. Both nuclei are attracted to the same pair
But sometimes one of the atoms is attracted to the electron pair much more strongly than the other. Basically, one atom gives its electrons to the other
Very high melting and boiling points
Metals and non metals form ionic compounds
Cation
Positive ion- metals
Anion
Negative ion- non metals
Formation of Ionic compounds
-The positively charged ions attract the negatively charged ions and arrange themselves into a 3D structure called an IONIC LATTICE
Bonds in Ionic compounds
The ionic bonds between the anions and cations are electrostatic forces of attraction.
The bonds are strong and there are many to break in an ionic crystal. A large amount of energy is required to overcome the forces- high boiling and melting points.
Mg2+O2- will have higher melting points than
Na+Cl-
Simple molecular substances
- At room temperature they are gases and liquids, or solids with very low melting and boiling points.
- This is because the forces of attraction are weak and so little energy is required to break
Protons and electrons
The atomic number is the number of protons in the atoms of the element, equal to the number of electrons. Elements in the same group have the same number of electrons in their outer shell (energy levels). This governs how they will react, so elements in the same group have similar chemical properties though there are differences from the top to the bottom of the group.
Metallic elements
- Group 1 and 2 are METALS
- The group between 2 and 3 are TRANSITION METALS
- The extra 2 rows are RARE EARTH METALS
- Group 3 (minus Boron) are METALS
- Tin and Lead from group IV are METALS
- Bismuth and Polonium from group V and VI are METALS
Boron, Silicon, Germanium, Arsenic and Antlimony are METALLOIDS
Subliming
Solid -> Gas
Group 1- Alkali metals: Elements
Lithium - Less dense than water, floats
Sodium -Less dense than water, floats
Potassium
Rubidium
Caesium
Francium