The first four alkanes are methane, ethane, propane, and butane with the Lewis symbols shown below.
Methane is the major constituent of natural gas. It is lighter than air and very flamable. Both of those properties are shown in the images below which feature physics professor Clint Sprott of the University of Wisconsin in his "Wonders of Physics" demonstration show. Natural gas is passed through a bubble mixture to produce bubbles on the order of 10 cm in diameter. As these bubbles rise, he touches a lighted candle to one of them.
Shipman, Wilson, Todd