What intermolecular forces act in the following: H2 PH3 CH3NH2
In order to identify the intermolecular forces present in each compound, we need to consider the molecular structure and the types of bonds within them.
1. H2 (hydrogen gas): The molecule consists of two hydrogen atoms bonded covalently. The only intermolecular force present is London dispersion forces, which results from temporary fluctuations in electron distribution that induce dipoles.
2. PH3 (phosphine): This molecule has a pyramidal structure with phosphorus and three hydrogen atoms bonded covalently. The intermolecular forces present are London dispersion forces and dipole-dipole interactions. The dipole-dipole interaction results from the polar bonds between phosphorus and hydrogen, creating a partial positive charge on the hydrogen atoms and a partial negative charge on the phosphorus atom.
3. CH3NH2 (methylamine): This compound consists of a central nitrogen atom bonded to three hydrogen atoms and a methyl group (CH3). The intermolecular forces present in CH3NH2 are London dispersion forces, dipole-dipole interactions, and hydrogen bonding. Hydrogen bonding occurs between the hydrogen atom attached to nitrogen and the lone pair of electrons on the nitrogen atom.
To summarize:
- H2: London dispersion forces
- PH3: London dispersion forces and dipole-dipole interactions
- CH3NH2: London dispersion forces, dipole-dipole interactions, and hydrogen bonding.
To determine the intermolecular forces present in a molecule, we need to consider the types of interactions between the individual molecules. The main intermolecular forces are:
1. London dispersion forces (also called van der Waals forces): These forces occur between all molecules, regardless of their polarity. They are caused by temporary fluctuations in the electron distribution, which induce a temporary dipole in nearby molecules. The strength of London dispersion forces increases with the size and shape of the molecules.
2. Dipole-dipole interactions: These forces occur between polar molecules that have a permanent dipole moment. A dipole is created when there is a significant electronegativity difference between the atoms in a molecule. The positive end of one molecule aligns with the negative end of another molecule, resulting in attractive forces between them.
3. Hydrogen bonding: This is a special type of dipole-dipole interaction that occurs when a hydrogen atom is bonded to an electronegative atom (such as nitrogen, oxygen, or fluorine). The hydrogen atom forms a hydrogen bond with a lone pair of electrons on another neighboring electronegative atom.
Now, let's analyze the intermolecular forces present in the given molecules:
1. H2: Hydrogen gas is non-polar and consists of diatomic molecules. It only experiences London dispersion forces since there are no polar bonds or lone pairs present.
2. PH3: Phosphine is a polar molecule since phosphorus is more electronegative than hydrogen. Thus, it experiences dipole-dipole interactions in addition to London dispersion forces.
3. CH3NH2: Methylamine is also a polar molecule. The central nitrogen atom has a lone pair of electrons, and there are three polar C-H bonds. Hence, it experiences dipole-dipole interactions and can also form hydrogen bonds between the nitrogen atom and the hydrogen atoms.
So, the intermolecular forces present in H2 are London dispersion forces, in PH3 are dipole-dipole interactions and London dispersion forces, and in CH3NH2 are dipole-dipole interactions, hydrogen bonding, and London dispersion forces.