(Topic 2) Bonding, Structure And Properties Of Matter (CGP Book) Flashcards
What are ions?
Charged particles
Can be single atoms or groups of atoms
When are ions made?
When electrons are transferred
Why do electrons transfer?
So the atoms can gain a full outer shell leading to a stable atom
What happens when metals form ions?
Lose electrons from outer shell to form positive ions
What happens when nonmetals form ions?
They gain electrons in their outer shell to form negative ions
What are positive ions known as?
Cations
What are negative ions known as?
Anions
What happens during ionic bonding?
Metal and nonmetal react together
Metal atom loses electrons to form positively charged ion
Nonmetal gains these electrons to form negatively charged ion
These charged ions are strongly attached to one another by electrostatic forces
What do Dot and cross diagrams show?
The arrangement of electrons in an atom or ion
What is ionic bonding?
Transfer of electrons
What type of structure do ionic compounds have?
A giant ionic lattice
How is an ionic compound structured?
Ions form are closely packed regular lattice arrangement and there are very strong electrostatic forces of attraction between oppositely charged ions
Properties of ionic compounds?
All have high melting points and high boiling points due to strong bonds between ions, it takes a lot of energy to overcome this attraction
When solid, ions are held in place so compounds cannot conduct electricity
When ionic compound melt ions are free to move and carry electric charge
Ionic compounds dissolve in water, the ions separate and are all free to move in the solution so can carry electric charge
What is covalent bonding?
Sharing electrons
What happens during covalent bonding?
Nonmetal atoms bond together
They share pairs for electrons to make covalent bonds
Positively charged nuclei of the bonded atoms are attracted to the shared pair of electrons by electrostatic forces making covalent bonds very strong
Atoms only share electrons in their outer shells
Each covalent bond provides one extra shared electron for each atom
Each atom involves generally enough covalent bonds to fill up its outer shell
Where does covalent bonding happen?
In compounds of nonmetals and in non-metal elements
What are simple molecular substances?
Made up of molecules containing a few atoms joined together by covalent bonds
Examples of simple molecular substances?
Hydrogen, chlorine, oxygen, nitrogen, methane, water, and hydrogen chloride
Properties of simple molecular substances?
Very strong covalent bonds, forces of attraction between these molecules are very weak
Melting and boiling points are very low
Most are gases or liquids at room temperature
As molecules get bigger strength of intermolecular forces increase some more energy is needed to break them so melting and boiling points increase
Do not conduct electricity as they are not charged so no free electrons or ions
What are polymers?
Long chains of repeating units
How are atoms in a polymer joined?
By strong covalent bonds
Properties of polymers
Most are solid at room temperature
Week into molecular forces so have lower boiling points than ionic or giant molecular compounds
What are giant covalent structures?
Macro molecules
How are atoms bonded in giant covalent structures?
By strong covalent bonds
