Ionic/Covalent/Metallic Bonding Flashcards
Describe ionic bonding in 3 words
Transfer of electrons
Describe ionic bonding in full
Metal + non-metal react together
metal loses electrons to become a cation
non-metal gains electrons to become an anion
These oppositely charged ions are strongly attracted to each other by electrostatic forces - an ionic bond
Draw the resultant dot and cross diagrams in these 2 scenarios
a) NaCl - the sodium gives up it’s outer electron, becoming an Na+ ion, the chlorine atom picks up the electron becoming a Cl- (chloride ion)
b) Na2O - 2 Na atoms each give up their single electron both becoming Na+ ions. The Oxygen atoms picks up 2 electrons becoming an 02-
a) [Na]+ [Cl]- These should both also have complete rings of electrons among them with the dots and crosses in the right place
b) [Na]+ [O]2- [Na]+ These should both also have complete rings of electrons among them with the dots and crosses in the right place. Also there could be a small 2 to the bottom right of the Na+ bracket to show there are 2 of them
define a covalent bond
A covalent bond is a strong bond that forms when a pair of electrons is shared between 2 atoms. Simple molecular substances are made up of molecules containing a few atoms joined by covalent bonds.
describe and draw the dot and cross diagrams for Methane (CH4) and Carbon dioxide (CO2)
CH4 - carbon has four outer electrons. it can form 4 covalent bonds with hydrogen atoms to fill up its outer shell
CO2 - in carbon dioxide molecules,a carbon atom shares 2 pairs of electrons with 2 oxygen atoms to form two double covalent bonds
List a few properties of Simple molecular substances
6
1) very strong covalent bonds. By contrast, the forces between the MOLECULES are very weak - like water
2) Melting and boiling points are very low as u only need to break these feeble intermolecular bonds and not the covalent bonds, because the molecules easily part
3) most molecular substances are gases or liquids at room temp
4) As the molecules get bigger so does the strength of the intermolecular forces therefore more energy needed to break them and higher melting and boiling points
5) Not conductors as the electrons aren’t free to move
6) with simple molecules some are soluble and some aren’t
what are polymers made from
covalently bonded carbon chains
Metallic bonding involves …
Delocalised electrons
describe some points about metallic bonding (not physical properties)
Metals consist of a giant structure (so do ionic compounds)
the electrons in the outer shell are delocalised and free to move around, meaning there’s a strong electrostatic attraction between positive metal ions and negative electrons
these forces of attraction hold the atoms together in a regular structure
Metallic bonding is very strong
alloys and elements are held together by metallic bonding
the delocalised electrons give the properties of metals
give the physical properties of metallic bonding
1) Metals need lots of energy to be broken due to strong electrostatic forces meaning they have high melting and boiling points
2) Metals are more dense due to the closer packing of atoms
3) the layers of atoms in pure metals can slide over each other making them malleable - can be hammered
4) Delocalised electrons carry electrical current and thermal energy through the material meaning they are good conductors of electricity and heat
difference in properties of metals and non-metals?
where are metals and non-metals usually found on the periodic table?
Non-metals have a wide variety in different structures so have a wide range of chemical and physical properties
NON-METALS tend to be dull looking, more brittle, have lower boiling points (not generally solids at room temperature) don’t generally conduct and often are less dense
Metals and non-metals have different chemical properties. non-metals tend to gain electrons to form full outer shells whereas metals do the opposite
Metals usually found on the left
non-metals usually found top right of the periodic table
explain the structure of an ionic compound
a) consisting of a regular arrangement of ions
b) held together by strong electrostatic forces (ionic bonds) between oppositely-charged ions
explain the properties of an ionic compound
a) high melting points and boiling points, in terms of forces between ions
b) whether or not they conduct electricity as solids, when molten and in aqueous solution
