G Tthe Atom
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Matter is made up of tiny particles called atoms. Atoms are too small to see, so scientists use models to explain their structure. Early models proposed atoms as indivisible spheres, while modern models show atoms with a tiny nucleus surrounded by electrons. The nucleus contains protons and neutrons, while electrons orbit around the outside. Atoms can form ions by gaining or losing electrons, changing their electrical charge but not their identity. Atoms of the same element can also vary in neutron number, forming isotopes of that element.
G Tthe Atom
- 2. Matter The term matter describes all of the physical substances around us: your table, your body, a pencil, water, and so forth
- 3. Matter Anything that has mass and takes up space (has volume) Made up of different kinds of atoms
- 4. Matter Includes all things that can be seen, tasted, smelled, or touched Does not include heat, sound, or light
- 5. Matter is made of atoms
- 6. Models Models are often used for things that are too small or too large to be observed or that are too difficult to be understood easily
- 7. Models In the case of atoms, scientists use large models to explain something that is very small Models of the atom were used to explain data or facts that were gathered experimentally. So, these models are also theories
- 8. Early Models of the Atom Democritus Universe was made of empty space and tiny bits of stuff Called these tiny bits of stuff atomos Atoms could not be divided
- 9. Early Models of the Atom Lavoisier Demonstrated that burning wood caused no change in mass Law of Conservation of Matter
- 10. Early Models of the Atom Dalton All elements are composed of indivisible particles. Atoms of the same element are the same Atoms of different elements are different. Compounds consisted of atoms of different elements combined together
- 11. Early Models of the Atom Thomson Plum pudding model Atom made of a positively charged material with the negatively charged electrons scattered through it.
- 12. Early Models of the Atom Rutherford Mostly empty space Small, positive nucleus Contained protons Negative electrons scattered around the outside
- 13. Early Models of the Atom Bohr Electrons move in definite orbits around the nucleus
- 14. Early Models of the Atom Chadwick Discovered the neutron
- 15. Modern Model of the Atom The called electron cloud Sometimes the wave model Spherical cloud of varying density Varying density shows where an electron is more or less likely to be
- 16. A closer look at quantum mechanics: http://www.fearofphysics.com/ Atom/atom1.html
- 17. Atomic Structure Nucleus – Protons – Neutrons Electrons
- 18. Atomic Structure Electrons Tiny, very light particles Have a negative electrical charge (-) Move around the outside of the nucleus
- 19. Atomic Structure Protons Much larger and heavier than electrons Protons have a positive charge (+) Located in the nucleus of the atom
- 20. Atomic Structure Neutrons Large and heavy like protons Neutrons have no electrical charge Located in the nucleus of the atom
- 21. Atomic Structure
- 22. Describing Atoms Atomic Number = number of protons In a neutral atom, the # of protons = the # of electrons
- 23. Describing Atoms Atomic Mass Number - equal to the number of protons plus neutrons.
- 24. Describing Atoms Atomic Weight - average mass of the naturally occurring isotopes of an element .
- 25. Ions An atom that carries an electrical charge is called an ion If the atom loses electrons, the atom becomes positively charged (because the number of positively charged protons will be more the number of electrons)
- 26. Ions An atom that carries an electrical charge is called an ion If an atom gains electrons, the atom becomes negatively charged (more negative charges than positive charges)
- 27. Ions The number of protons does not change in an ion The number of neutrons does not change in an ions So, both the atomic number and the atomic mass remain the same.
- 28. Ions This atom has lost an electron. Now it has one more proton than electron. One more proton means one more positive charge. This makes the total charge of the atom POSITIVE. This atom has gained an electron. Now it has one less proton than electron. One less proton means one less positive charge. This makes the total charge of the atom NEGATIVE.
- 29. Isotopes The number of protons for a given atom never changes. The number of neutrons can change. Two atoms with different numbers of neutrons are called isotopes
- 30. Isotopes Have the same atomic number (number of protons) Have different atomic mass numbers (number of protons + neutrons)
- 31. Isotopes