11.2 Density

11.2 Density

• A rock is a solid.
• The rock's shape is due to the forces holding its atoms together.
• They resist attempts to push them closer together and hold them in close contact.
• Water is a liquid.
• The water is in an open container because of the forces between its atoms.
• A closed container is needed to hold a gas to prevent it from moving.

• There are forces between the atoms that allow them to vibrate but not change their positions.
• A solid is resistant to all types of stress.
• The atoms that make up the solid are not able to move freely.
• Solids are resistant to compression because their atoms form part of a lattice structure in which the atoms are a fixed distance apart.
• The atoms would be forced into each other.
• Most of the examples we have studied involve solid objects which don't change much when stressed.

• Solids and fluids have atomic and molecular characteristics.
• The Things Great and Small features of the text highlight the submicroscopic explanation.
• It is possible to see a description of pressure in a gas.
• This section is devoted to the submicroscopic explanation of liquids.

• Liquids do not spring back to their original shape once the force is removed because the atoms are free to slide about and change neighbors, so they are a type of fluid.
• If the container has no holes below the surface of the liquid, it will remain in the container.
• Liquids are closely packed and resist compression.

• Atoms in gases and charged particles are separated by large distances compared to the size of the particles.
• When the particles collide, the forces between them are very weak.
• Gases and plasmas are not only fluids, but they are also easy to compress because there is little force between the particles.
• Liquids will escape when placed in an open container.
• Liquids are not compressed as easily as gases are.
• They have a lot of energy and are difficult to contain.

• As they change between solid, liquid, and gas phases, watch as atoms and molecules are heat, cool, and compressed.

• There is a distinction between mass and density.
• We are tempted to think of bricks as heavier than feathers because of their higher density.

• It's important to determine whether an object sinks or floats in a fluid.
• The mass per unit volume of an object is called density.
• The Greek letter rho is the symbol for density, the mass, and the volume occupied by the substance.

• Mass per unit volume is called density.

• The mass of the bricks and feathers is the same, but the volume occupied by the feathers is much higher.
• The representative values are given in Table 11.1.
• The metric system was designed so that water would have a density equivalent to.
• The kilogram was first created to be the mass of 1000 mL of water, which has a volume of 1000 cm3.

• The feathers make a bigger pile than the bricks because of their lower density.

• The density of an object may help identify its composition.
• The density of gold is 2.5 times that of iron and 2.5 times that of aluminum.
• The phase of the matter and its substructure are revealed by Density.
• The densities of liquids andsolids are roughly the same, consistent with the fact that their atoms are in close contact.
• The densities of gases are less than those of liquids andsolids because the atoms in gases are separated.

• If the volumes of both piles are the same, the difference in mass is due to their different densities.

• The density of water can be found in Table 11.1.