Density of a quantity of matter is its mass divided by its volume. External pressure pushes the atoms or molecules closer together and increased temperature usually expands the volume of the material, pushing the molecules apart. A change in the phase or state of a material usually results in a change in density.

However, the density does not change. This is because the mass and volume increase at the same rate/proportion!

This variation is typically small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases the volume of the object and thus increases its density. Increasing the temperature of a substance (with a few exceptions) decreases its density by increasing its volume.

gases

Solid is of highest density due to its close packing of molecules inside a substance there is no space between the molecules and they are closely and linearly arranged inside the given surface.

The first chemical element with the lowest density is Hydrogen and the highest density is Osmium.

lithium

New Magnesium based alloy as World’s strongest and lightest metal to change the world: Researchers from North Carolina State University have developed a material using magnesium which is light like aluminum, but as strong as titanium alloys. This material has the highest strength-to-weight ratio known to mankind.

lithium, sodium and potassium are less dense than water so they float on the surface of the water. the metals move about the surface of the water and fizz as hydrogen gas is produced.

To compare the density of two substances like clay and water, you can compare the weight of the same “size” or volume, of each substance. As you show the animation, explain that since a piece of clay weighs more than the same amount, or volume, of water, clay is more dense than water.

Potassium has a density of 0.862 g/cm3 while sodium has a density of 0.971 g/cm3. All of the other metals on the periodic table are denser than water. While lithium, potassium, and sodium are all light enough to float on water, they are also highly reactive.

Sodium, potassium and lithium are the metals which can float on water because they are less dense than pure water. Also, being highly reactive, these metals react with water and burn or explode.

A steel bar dropped into water sinks, but a boat made of steel floats. Because most of the space in a boat is taken up by air. Taken as a whole, this makes the boat much less dense than the steel bar, and even less dense than water.