Head:

* Carboxylic acid group (-COO-)

* This group is polar and attracts water molecules, making it hydrophilic.

* Ionic bond to a metal cation (e.g., Na+, K+)

* This creates a charged head, further increasing its solubility in water.

Tail:

* Long hydrocarbon chain (typically 12-18 carbon atoms)

* This chain is nonpolar and hydrophobic, meaning it repels water but attracts grease and oil.

Here's a simplified diagram of a soap molecule:

```

O

||

-C-O-Na+

|

CH3-(CH2)n-

|

...

|

CH3

```

How it works:

The hydrophobic tail of the soap molecule interacts with grease and oil, while the hydrophilic head interacts with water. When soap is added to water and grease, the soap molecules surround the grease droplets, forming micelles. The hydrophobic tails face inwards towards the grease, while the hydrophilic heads face outwards towards the water. This allows the grease to be suspended in water and eventually washed away.