C2 - Simple Molecular Substances Flashcards
What are simple molecular substances made up of?
Molecules containing a few atoms joined together by covalent bonds.
Examples of simple molecular substances
- Hydrogen H2
- Chlorine Cl2
- Oxygen O2
- Nitrogen N2
- Methane CH4
- Water H2O
- Hydrogen Chloride HCl
- Ammonia NH3
What type of covalent bond does hydrogen form?
They often form single covalent bonds as they only need one electron for an outer shell,often with other hydrogen atoms or a group 7 element
What type of covalent bond does chlorine form?
They form a single covalent bond as they only need one more electron to form an outer shell,usually with another chlorine atom to form a full outer shell
What type of covalent bond does oxygen form?
As oxygen needs two more electrons to complete its outer shell,in oxygen gases they share two pairs of electrons with each other making a double covalent bond
What type of covalent bond does nitrogen form?
Nitrogen needs three more atoms to form a full outer shell so two nitrogen atoms share three pairs of electrons to fill their outer shells.This creates a triple bond
What type of covalent bond does methane form?
Carbon has four outer electrons which is half a full shell,so it can form four covalent bonds with hydrogen atoms to fill up its outer shell
(Methane is CH4)
What type of covalent bond does water form?
In water molecules,the oxygen shares a pair of electrons with two hydrogen atoms to form two single covalent bonds for a full outer shell
(Water is H2O)
What type of covalent bond does hydrogen chloride form?
Both atoms only need one more electron to form their outer shells so it is a single covalent bond
How are the atoms between the molecules held together by?
The atoms within the molecules are held together by very strong covalent bonds. By contrast, the forces of attraction between these molecules are very weak.
How do you melt or boil a simple molecular substance?
To melt or boil a simple molecular compound, you only need to break these feeble intermolecular forces and not the covalent bonds. So the melting and boiling points are very low, beause the molecules are easily parted from each other.
What state are most molecular substances at for room temperature?
Gases or liquids
What happens as molecules get bigger?
As molecules get bigger the strength of the intermolecular forces increases, so more energy is needed to break them, and the melting and boiling points increase
Why do molecular compounds not conduct electricity?
As they are not charged,so there are no free electrons or ions
