Atoms - Chandler Unified School District

Atoms - Chandler Unified School District

Atoms Atomic Theory As early as 400 BC, a few people believed that atoms are the building blocks of all matter. Yet, until recently, even scientists had never seen evidence of atoms. More than 2000 years later, scientists found evidence that supported this idea.

The Greek philospher Democritus proposed in 440 B.C. that matter was made of very tiny particles he called atomos. (Greek: atomos= not to be cut) Alchemists

Before there were chemists, there were alchemistsscientists who wanted to find methods to turn common metals into gold. The alchemists practiced, often in secret, throughout the world during the Middle Ages. Although they were never successful in their quest for gold, alchemists provided much information and helped establish chemistry as a science. Daltons Atomic Theory

In 1808, John Dalton, an English school teacher proposed the first Atomic Theory. Dalton showed that elements are composed of only one kind of atom and compounds are made of two or more kinds of atoms. Daltons 5 Principles: 1.

All matter is composed of extremely small particles called atoms, which cannot be subdivided, created, or destroyed. According to Dalton, atoms cannot be broken into smaller pieces. Daltons 5 Principles: 2. Atoms of a given element are identical in their physical and chemical properties. In any element,

all atoms are exactly alike. Atoms of each element have the same mass. Carbon atom Daltons 5 Principles: 3. Atoms of different elements differ in their physical and chemical properties. Atoms of different elements are different, particularly in

their mass. Hydrogen atom Silicon atom Oxygen atom Daltons 5 Principles: 4. Atoms of different elements combine in simple,

whole-number ratios to form compounds. Daltons 5 Principles: 5. In chemical reactions, atoms are combined, separated, or rearranged but never created, destroyed, or changed. According to Dalton, atoms are indestructible. The combustion of methane and oxygen

forms water and carbon dioxide. Note that the numbers and types of atoms are the same. All atoms are accounted Todays Atomic Theory Today, scientists can divide an atom into even smaller particles and can destroy and create atoms.

For example, in 2006, at Russia's Joint Institute for Nuclear Research, scientists produced 3 atoms with 118 protons. All it took was smashing "bullets" of calcium at a target of Californium about 10,000,000,000,000,000,000 times. Each atom lived only a fraction of a millisecond before decaying! Structure of Atoms In the mid-1800s scientists discovered that atoms

can be broken into pieces after all. The smaller parts that make up atoms are called subatomic particles. Electrons (- charged) Protons (+ charged) Neutrons (neutral) Atoms have a Nucleus The nucleus is the dense, central portion of the

atom. The nucleus has all of the positive charge, nearly all of the mass but only a very small fraction of the volume of the atom. If an atom the size of a sewing pin was placed in the middle of the 50 yard line on a football field, the electrons would be orbiting around the goal posts! Most of an atom is empty space!

Protons and Neutrons Compose the Nucleus Protons are subatomic particles that have a positive charge and are found in the nucleus. The number of protons in the nucleus is the atomic number, which identifies the element. Neutrons are subatomic particles that have no charge and are located

in the nucleus. Neutrons add mass to the atom. Isotopes Isotopes are atoms of an element that have the same number of protons, but a different number of neutrons. Most isotopes are rare. An isotope is identified by its atomic mass

number. The atomic mass number is the total number of protons + neutrons in the nucleus of the atom. What is the difference between these 3 atoms? How to Identify an Isotope Look at the atomic mass of the element on the periodic table. Remember that each proton

weighs 1 atomic mass unit (amu). Each neutron also weighs 1 amu. If the atom has the same mass as is shown on the periodic table, it is NOT an isotope. If the atom has a different mass, (but the same number of protons), then it IS an isotope.

Recently Viewed Presentations

  • Environmental Regulationis - University of Arizona

    Environmental Regulationis - University of Arizona

    Decentralized PoliciesLiability Laws. Liability: To be liable for some behavior is to be held responsible for whatever untoward consequences result from that behavior. Compensation: requires that those causing the damage compensate those damaged in amounts appropriate to the extent of...
  • 'young boys, no trouble, very safe'? Frédéric Mitterrand's La ...

    'young boys, no trouble, very safe'? Frédéric Mitterrand's La ...

    J'imaginais Tony Leung à vingt ans (293-4). Nous sommes seuls. ... Laurence Ferrari, je n'ai jamais fait de mal à personne dans ma vie. Jamais. On fait toujours un peu de mal à des gens, mais là on parle de...
  • Chapter 24: Rhetoric and Humor by Don and

    Chapter 24: Rhetoric and Humor by Don and

    Other concealed oxymorons include "young senator," "typed manuscript," and "old novel." * Doggerel is bad, but intentional doggerel is sometimes just fine. * GOOD DOGGEREL I love you more than a duck can swim, And more than a grapefruit squirts,...
  • History of Comics

    History of Comics

    "Same Song" By Pat Mora While my sixteen-year-old son sleeps, my twelve-year-old daughter stumbles into the bathroom at six a.m. plugs in the curling iron squeezes into faded jeans curls her hair carefully strokes Aztec Blue shadow on her eyelids...
  • Chapter Three: Supporting Details

    Chapter Three: Supporting Details

    Vocabulary in Context Objective: Determine the meaning of words and phrases as they are used in the text, including figurative, connotative, and technical meanings.
  • Theme Based Instruction - Kristin's Art Box

    Theme Based Instruction - Kristin's Art Box

    You have probably been introduced to the Smith and Ragan process model in previous classes. This instructional module on Theme Based Instruction (TBI) is meant to help you learn about another approach to instruction to further enhance your knowledge base.
  • NSLS  II ASAC Review Conventional Facilities Briefing Marty

    NSLS II ASAC Review Conventional Facilities Briefing Marty

    Title: No Slide Title Document presentation format: On-screen Show Other titles: Times New Roman Osaka Times Arial Narrow Wingdings Wingdings 2 1_Blank Microsoft Photo Editor 3.0 Photo Microsoft Word Document Adobe Acrobat Document NSLS - II ASAC Review Outline NSLS...
  • COMMUNICATION IN THE 21ST CENTURY Interpersonal Communication COMA

    COMMUNICATION IN THE 21ST CENTURY Interpersonal Communication COMA

    Computer-Mediated Communication. CMC: Communication between and among people through the medium of computers (includes e-mail, chat rooms, bulletin boards, and newsgroups).