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Exploring Atoms and Elements: The Building Blocks of Matter

Discover the wonders of atoms and elements, the fundamental units of matter that compose everything around us. Learn about their properties, names, and historical discoveries that shaped our understanding. Delve into the fascinating world of chemistry!

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Exploring Atoms and Elements: The Building Blocks of Matter

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  1. Atoms and elements

  2. Matter…. • Is Everything! • It’s the amount of mass in an object • Measured in kilograms • It has volume: takes up space • Measured in milliliters or cubic centimeters • All matter is composed of elements • only about 50 basic elements Analogy: alphabet letters – words – sentences – books!

  3. Elements are… • Purest of the pure substances • There are 112 of them known so far • They are organized on the Periodic Table • The most common elements: 1. oxygen ( air, water, rock, living things) 2. Hydrogen (water, living things, sun, stars) 3. Nitrogen (air 80%, living things, soil) 4. magnesium, iron, aluminum, carbon

  4. Old Atomic Symbols The original chemical symbols of some of the older known elements were just that, symbols

  5. Naming elements • Physical properties such as their COLOR • Scientist: • Places: • Latin names: • Greekmythology: rubidium Curium, Einsteinium, Rutherfordium, Fermium Californium, Americinium, Europium Aurum (gold), Argentium (silver), Plumbium (copper) Helios (helium), mercury, plutonium

  6. Atomic Symbol • Universal (all countries) use the same symbols • 1 or two letter symbol • First letter is alwaysCAPITOL, second letter always lower case. Co (cobalt) is not same as CO (carbon monoxide) • Examples: • C for carbon • Ca for calcium • Cl for chlorine • Cf for californium CF C F Cf Not correct!!!

  7. fire earth air water Aristotle Early Greek Theories • 350 B.C - Aristotle • Theory that matter was made of four “elements”: earth, fire, water, air. • Aristotle was wrong. However, his theory persisted for 2000 years.

  8. The Greeks • 300 B.C. • Democritus a greek philosopher • The smallest “piece” of matter you could have: atomos: indivisible • They named the atom

  9. Atoms • Smallest part of an element. • Too small to be seen in ordinary light. • All atoms are made of the same basic ‘ingredients’ • Atoms vary in size and mass.

  10. John Dalton • 1800’s • Atoms are seen as solid, indestructible spheres (like billiard balls) • Proposed an Atomic Theory which states; - -Atoms of the same element have the same kind of atoms. -Atoms of different elements have different kinds of atoms. -Compounds are composed of atoms combined in specific ratios. -Atoms combine and rearrange yet mass is conserved Jelly beans

  11. The Electron • 1850’s • J. J. Thomson • A gas beam was repelled away by a magnet. • The gas is made of atoms, so…. • atoms must contain CHARGED particles! Magnet The beam was repelled (away) from the magnet!

  12. Thomson’s atomic model • Thomson found that there were small electrons embedded in the atom like chocolate chips in a chocolate chip cookie. • Atoms are solid spheres made-up of a solid positive mass (cookie) with tiny negative particles embedded in the positive core Negative electrons Positively charged cookie.

  13. Thomson’s electron model • Electrons are very small negatively charged particles. • (1/2000 the mass of a proton)

  14. Nucleus • 1905. Discovered by Earnest Rutherford in his famous ‘gold foil’ experiment. • He shot positively charged particles at a very thin piece of gold foil. He expected the particles to go right through the gold foil • But a few BOUNCED BACK! • THEY HIT SOMETHING SOLID!

  15. Rutherford’s gold foil experiment • This proved that: • the atom had a dense but very small positive core • the electrons were far away from the nucleus • Most of the atom is just EMPTY SPACE!

  16. That would be like a basketball (nucleus) on the 50 yard line, and you were an electron in a seat way up in the stands.

  17. Rutherford summarized that the nucleus must be… • Very small, dense,solid center of the atom • The nucleus has a positive charge • The electrons (negative) must be around the outside. • Most of the atom is empty space.

  18. Proton • Dense, positively charged particle • There are equal #of protons and electrons in a neutral atom. + = - • Proton # is their Atomic number. Ex: 6 protons is element 6 or carbon

  19. Neutron • Difficult to ‘find’ because they have no charge • Same mass as a proton, but has NO CHARGE (neutral) • Neutrons are in the nucleus. No charge

  20. Neils Bohr • 1920’s • Electrons move in orbits or energy levels around  the nucleus • Electrons can “jump” to different energy levels if they gain or lose energy.

  21. Quantum Mechanical Modelor Electron Cloud Model • Electrons move around the nucleus very fast. • You can’t predict where an electron will be at any moment. (Heisenburg Principle) • The analogy here is that of a "beehive" where the bees are the electrons and they ‘buzz’ around the nucleus.             

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