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-atoms as a source of nuclear energy.

-an extremely small amount of a thing or quality.

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One Hour Of Mind-Blowing Mysteries Of The Atom | Full Documentary

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Are all atoms the same size?

What does the mass of an atom consist of?

How is the atomic number of an atom defined?

atom, the basic building block of all matter and chemistry. Atoms can combine with other atoms to form molecules but cannot be divided into smaller parts by ordinary chemical processes.

Most of the atom is empty space. The rest consists of three basic types of subatomic particles: protons, neutrons, and electrons. The protons and neutrons form the atom's central nucleus. (The ordinary hydrogen atom is an exception; it contains one proton but no neutrons.) As their names suggest, protons have a positive electrical charge, while neutrons are electrically neutral-they carry no charge; overall, then, the nucleus has a positive charge. Circling the nucleus is a cloud of electrons, which are negatively charged. Like opposite ends of a magnet that attract one another, the negative electrons are attracted to a positive force, which binds them to the nucleus. The nucleus is small and dense compared with the electrons, which are the lightest charged particles in nature. The electrons circle the nucleus in orbital paths called shells, each of which holds only a certain number of electrons.

An ordinary, neutral atom has an equal number of protons (in the nucleus) and electrons (surrounding the nucleus). Thus the positive and negative charges are balanced. Some atoms, however, lose or gain electrons in chemical reactions or in collisions with other particles. Ordinary atoms that either gain or lose electrons are called ions. If a neutral atom loses an electron, it becomes a positive ion. If it gains an electron, it becomes a negative ion. These basic subatomic particles-protons, neutrons, and electrons-are themselves made up of smaller substances, such as quarks and leptons.

More than 90 types of atoms exist in nature, and each kind of atom forms a different chemical element. Chemical elements are made up of only one type of atom-gold contains only gold atoms, and neon contains only neon atoms--and they are ranked in order of their atomic number (the total number of protons in its nucleus) in a chart called the periodic table. Accordingly, because an atom of iron has 26 protons in its nucleus, its atomic number is 26 and its ranking on the periodic table of chemical elements is 26. Because an ordinary atom has the same number of electrons as protons, an element's atomic number also tells how many electrons its atoms have, and it is the number and arrangement of the electrons in their orbiting shells that determines how one atom interacts with another. The key shell is the outermost one, called the valence shell. If this outermost shell is complete, or filled with the maximum number of electrons for that shell, the atom is stable, with little or no tendency to interact with other atoms. But atoms with incomplete outer shells seek to fill or to empty such shells by gaining or losing electrons or by sharing electrons with other atoms. This is the basis of an atom's chemical activity. Atoms that have the same number of electrons in the outer shell have similar chemical properties.

This article opens with a broad overview of the fundamental properties of the atom and its constituent particles and forces. Following this overview is a historical survey of the most influential concepts about the atom that have been formulated through the centuries.

Most matter consists of an agglomeration of molecules, which can be separated relatively easily. Molecules, in turn, are composed of atoms joined by chemical bonds that are more difficult to break. Each individual atom consists of smaller particles-namely, electrons and nuclei. These particles are electrically charged, and the electric forces on the charge are responsible for holding the atom together. Attempts to separate these smaller constituent particles require ever-increasing amounts of energy and result in the creation of new subatomic particles, many of which are charged.

As noted in the introduction to this article, an atom consists largely of empty space. The nucleus is the positively charged centre of an atom and contains most of its mass. It is composed of protons, which have a positive charge, and neutrons, which have no charge. Protons, neutrons, and the electrons surrounding them are long-lived particles present in all ordinary, naturally occurring atoms. Other subatomic particles may be found in association with these three types of particles. They can be created only with the addition of enormous amounts of energy, however, and are very short-lived.

All atoms are roughly the same size, whether they have 3 or 90 electrons. Approximately 50 million atoms of solid matter lined up in a row would measure 1 cm (0.4 inch). A convenient unit of length for measuring atomic sizes is the angstrom (Å), defined as 10 −10 metre. The radius of an atom measures 1-2 Å. Compared with the overall size of the atom, the nucleus is even more minute. It is in the same proportion to the atom as a marble is to a football field. In volume the nucleus takes up only 10 −14 metres of the space in the atom-i.e., 1 part in 100,000. A convenient unit of length for measuring nuclear sizes is the femtometre (fm), which equals 10 −15 metre. The diameter of a nucleus depends on the number of particles it contains and ranges from about 4 fm for a light nucleus such as carbon to 15 fm for a heavy nucleus such as lead. In spite of the small size of the nucleus, virtually all the mass of the atom is concentrated there. The protons are massive, positively charged particles, whereas the neutrons have no charge and are slightly more massive than the protons. The fact that nuclei can have anywhere from 1 to nearly 300 protons and neutrons accounts for their wide variation in mass. The lightest nucleus, that of hydrogen, is 1,836 times more massive than an electron, while heavy nuclei are nearly 500,000 times more massive.

Basic properties

The single most important characteristic of an atom is its atomic number (usually denoted by the letter Z), which is defined as the number of units of positive charge (protons) in the nucleus. For example, if an atom has a Z of 6, it is carbon, while a Z of 92 corresponds to uranium. A neutral atom has an equal number of protons and electrons so that the positive and negative charges exactly balance. Since it is the electrons that determine how one atom interacts with another, in the end it is the number of protons in the nucleus that determines the chemical properties of an atom.

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Atom | Definition, Structure, History, Examples, Diagram, & Facts

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Atom, smallest unit into which matter can be divided without the release of electrically charged particles. It also is the smallest unit of matter that has the characteristic properties of a chemical element. As such, the atom is the basic building block of chemistry.

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a stable subatomic

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Why Protons Are Still Such a Mystery to Scientists

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****Please copy this in your notebook or ask for a copy, will be on the test Friday.****

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The proton is a subatomic particle with a positive electrical charge.

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Homework please read chapter 1 on atoms and chapter 2 on protons. Please be prepared to answer the questions that are from these chapters. 

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Homework please read chapter 1 on atoms and chapter 2 on protons. Please be prepared to answer the questions that are from these chapters. 

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The neutron is a subatomic particle, symbol n or , with no net electric charge and a mass slightly larger than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons behave similarly within the nucleus, and each has a mass of approximately one atomic mass unit, they are both referred to as nucleons.

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What Are the Characteristics of Electrons? | Chemistry Matters

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look at how the atom looks and does in cold

and hot water.

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How Atoms react in Hot and Cold Water.  Science Experiment for Kids.

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Nasa's cold atom lab, this is cool video, I hope you all like it as much as I do.

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NASA’s Cold Atom Lab: The Coolest Experiment in the Universe

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Make sure you have written notes in your notebook,

Please make sure you have your notebook in class.

Sleep well, so you can ALL ACE the test.

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HAVE YOUR NOTES!!! YOU CAN DO THIS!!!

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Review Periodic Table, please pick an element,

please note no two students will have the same element.

We will have a sign up sign available Monday morning.

Have a great weekend, see you all Monday.

-Ms. Salcedo

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It's not an animal, mole, we will discuss "the moles"

in Chemistry.

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Get a goodnight's sleep.

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Be prepared for a quiz Thursday before class. Remember to read chapter 3 and 4.

There will be a Test on Friday please make sure you have written notes in your notebook,

it could be a open book test... so prepare yourselves. -Ms. Salcedo

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Follow us at: https://plus.google.com/+tutorvista/ Check us out at http://chemistry.tutorvista.com/nuclear-chemistry/protons-and-neutrons.html Neutrons The neutron is a subatomic particle with no net electric charge and a mass slightly larger than that of a proton. They are usually found in atomic nuclei. The nuclei of most atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons.

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For extra credit please write a 1 page paper about atoms and where they are found. Due  in class Monday morning. 

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For extra credit please write a 1 page paper about atoms and where they are found. Due  in class Monday morning. 