How can two same sized and shaped things have different masses? Copper and aluminum atoms may be organized differently, allowing for more copper atoms to fit into the same size cube. Volume is a measurement of how much space a thing occupies. Grams are used to measure mass. The gram is the mass of 1 cubic centimeter of water at 4 degrees Celsius (40 degrees Fahrenheit). So, if you had two things that occupied the same volume but had different numbers of atoms in their composition, they would have different weights.
Atoms are the smallest components of molecules. Molecules are made up of atoms combined together. If you were to divide each atom inside of a given substance by its atomic number, then the result would be the number of grams in one pound (or kilogram). For example, if we look at iron, it has 26 protons in its nucleus and therefore has a nuclear weight of 58.718360096G. To find its atomic weight, we simply divide 58.718360096 by the atomic number of iron, which is 56.
Iron has a large number of electrons in its outer shell, so it is magnetic. Nickel has only 28 electrons in its outer shell, so it is not magnetic. Carbon has 6 electrons in its outer shell, so it is not magnetic either. Silicon has 14 electrons in its outer shell, so it is magnetic.
An object's mass is equal to its volume multiplied by its (average) density. Two items of the same size can have different masses, and two objects of quite different sizes can have the same mass: it's all in the densities. If you double the density of some material then it will take up twice as much space but still weigh the same as before.
Here are some examples: if you double the density of water then a cup full of water would weigh eight times as much; if you doubled the density of air then a box of air would weight four times as much. None of these things actually happen in reality but they do in theory! The key point is that the mass of any object is fixed. You cannot make one object out of two different materials with different properties. They will always have different masses.
This is important because people often think that something can be made out of nothing if you break it down into its basic components. For example, atoms are thought to be made from energy which can be seen as particles called photons which have no mass but still contribute to the energy of an object after they interact with it. So someone might say that energy is "made" of atoms which are made out of empty space. This is not true though; energy cannot be created or destroyed but it can be changed from one form to another.
Is bulk synonymous with size? No, mass is not the same as size or volume. This is due to the fact that the mass is determined by the sort of atoms or molecules as well as their density. The higher the number of particles of any type within a given space, then there will be more mass in that space. Even if the particles are all the same type, such as electrons, they still account for different masses because of their different numbers. For example, one cup of water contains about 1 kg (2 lb 4 oz) of mass but it's made up of hundreds of millions of small particles called molecules. Each molecule has two types of atoms: hydrogen and oxygen. There are about a million molecules in the cup of water.
Mass is a measure of matter's intrinsic worth, or its "heavyness." It is the factor by which matter resists change, i.e., its inertia. Mass is proportional to gravity's effect on an object, so objects with greater mass fall faster than objects with less mass. This relationship holds for bodies at rest with respect to each other as well as for bodies in motion through space; thus, mass is always relative to some reference point. An object's mass can change due to chemical reactions or changes in the object's composition, but only over very large time scales compared to the age of the universe.
However, if the densities of two things of the same volume differ, their masses will differ as well. Because "density" is defined as mass divided by volume, if the volumes are the same but the densities differ, the masses must likewise differ. For example, imagine that you pour eight 1-pound rocks into a single 2-pound plastic bag. The rocks fill the bag, but only seven of them fit in an area no more than 1/4 inch thick. The remaining rock has a density higher than 7/8 pound per cubic inch, so its mass would exceed 2 pounds even though the bag is still only half full.
Density is related to mass and composition. Some elements are lighter than others of the same size. For example, hydrogen is less dense than helium, which is less dense than carbon, which is less dense than oxygen, etc. All together, these elements make up our planet Earth. Rock is made up of atoms joined together, with empty spaces between them. The amount of space per unit weight increases as we go up the sequence (i.e., water is less dense than ice, which is less dense than steel).
Density is also affected by shape.
M = d v, where d denotes density and v denotes volume. If you double the volume of a material while keeping its mass the same, then its density must also double.
There are many examples in nature of substances with identical atoms but different masses or densities. For example, water is composed of two hydrogen atoms and one oxygen atom, but each element has its own specific weight so that water is heavier than hydrogen or oxygen alone. The relative weights of these elements in water are H 2 O.
The mass of a substance is measured using a mass spectrometer, which measures the amount of matter in an object. The matter consists of electrons orbiting nuclei, but since electrons are much lighter than nuclei, only the mass of the nuclei is actually being measured when using a mass spectrometer.
When scientists talk about the density of a substance, they are talking about the ratio of its mass to its volume. This is similar to the way that we measure the strength of materials: We use the weight per unit area rather than the total weight. Density plays an important role in physics because it is always used when comparing quantities such as pressures or energies between different objects.