PARTS OF AN ATOM AND CHARGE OF ATOMIC PARTICLES

You have a cube of sugar in your hand, which you break into smaller pieces.  You then grind those pieces into even smaller pieces and dissolve the smaller pieces in a glass of water.  In the glass of water, the sugar can no longer be seen, yet, by tasting the water, it is evident that the sugar is still there. It has not been destroyed or changed to another form of matter. Sugar is a compound made of 3 elements (Carbon, oxygen, and hydrogen). Find these three elements C, O, and H on the periodic table.

In science, the smallest particle that can exist and still have the element's properties is called an atom. Science has developed many models throughout our scientific history to describe or illustrate the makeup of an atom.

Each atom comprises smaller particles—electrons, protons, and neutrons. These are called subatomic particles. At the center of an atom is a nucleus. The nucleus consists of protons and neutrons. Protons carry a positive electrical charge, while neutrons carry no electrical charge. Together, protons and neutrons are called nucleons. Surrounding the nucleus is a cloud of negatively charged electrons.

Scientists believe that subatomic particles—protons, neutrons, and electrons—are themselves made up of smaller substances. The substances are called quarks and leptons.

The currently popular model was developed in 1926 and is called the electron cloud model.  In the case of an atom, models are used to describe or illustrate something too small to see.  Models can also be used to describe or illustrate something too large to view.  An example of something too large would be a model of our solar system.  We cannot see all of the planets in our solar system when we look at our sky, so a model allows us to grasp conceptually what our solar system looks like.

All atoms have the same essential parts. These are a nucleus, and at least one particle called an electron. The nucleus contains protons and neutrons.

The model of an atom shows the center of an atom as the nucleus, which contains two particles: the proton, a particle with a positive charge, and the neutron, a particle with no charge. Both protons and neutrons have mass, and their mass in the nucleus represents nearly all the mass of the atom. Since the nucleus contains particles with no charge and particles with a positive charge, a nucleus has an overall positive charge. Most of the atom is space. Ernest Rutherford discovered this. Because the atom is too small for us to see, we use a model to understand better how it works. If the atom was the size of the Astrodome, the nucleus could be represented by a marble placed on the pitcher's mound.

The number of protons in a nucleus is called the atomic number.  Carbon has an atomic number of 6 which means that it has 6 protons in the nucleus, sulfur (S) has 16 protons, and lead (Pb) has 82 protons.  The proton number is what makes each element unique.

An atom is electrically neutral.  Therefore, if the center of an atom is positive, there must be a negative atom area.  There is a region outside of a nucleus called the electron cloud, which contains particles called electrons.  Electrons have no mass, and they have a negative charge.  Using our previous example of Carbon, it is known that the atomic number is six, and we also know the number of protons determines the atomic number, so Carbon has 6 protons.  Since an atom must be neutral in charge, it must contain the same number of electrons and protons; therefore, Carbon has 6 electrons, sulfur 16 electrons, lead 82 electrons

Atoms do have mass even though they are minimal.  The atom's mass is in the protons and neutrons.  A proton has one mass; this is called an atomic mass unit.  A neutron has one mass; this is called an atomic mass unit.   Electrons are so small they have a mass too small to consider.  Atomic mass is the sum of the number of protons and neutrons. Everything is made of atoms.  Your body is made of atoms. When you stand on a scale to measure your weight, you measure the mass of all your protons and neutrons.