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Unit 2-4 Atomic structure

Unit 2-4 Atomic structure. Atoms. Elements are made of particles called atoms Atoms are the smallest pieces of matter that contain all the properties of a specific element Each element contains only one type of atom. Inside the Atom. Atoms are made up of smaller particles

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Unit 2-4 Atomic structure

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  1. Unit 2-4 Atomic structure

  2. Atoms • Elements are made of particles called atoms • Atoms are the smallest pieces of matter that contain all the properties of a specific element • Each element contains only one type of atom

  3. Inside the Atom • Atoms are made up of smaller particles • These particles are found in different regions of the atom

  4. Current Atomic Theory • Nucleus: • contains protons and neutrons • takes up very little space • contains most of the mass • Electron Cloud: • contains electrons • takes up most of space • Electrons not found in absolute locations, but rather highest area of probability

  5. Nucleus • The nucleus is the positively charged dense core in the center of the atom • Contains 99.9% of mass of atom • Houses protons and neutrons

  6. Electron Cloud • Region around nucleus • Houses electrons

  7. Size of an atom • Atoms are small. • Measured in picometers, 10-12 meters. • Hydrogen atom, 32 pm radius. • Nucleus tiny compared to atom. • If the atom was the size of a stadium, the nucleus would be the size of a marble.

  8. Subatomic particles Actual mass (g) Relative Mass (amu) Name Symbol Charge 9.11 x 10-28 Electron e- -1 1/1840≈ 0 1.67 x 10-24 Proton p+ +1 1 1.67 x 10-24 Neutron n0 0 1

  9. Subatomic Particles • number of protons identifies the atom as a certain element • protons and neutrons are about same size and mass of 1 atomic mass unit (amu) among • electrons are much smaller – mass is ~1/2000th of a proton or neutron • nuclear force- it’s what hold the nucleus together • when particles in the nucleus get very close, they have a strong attractions for each

  10. Valence Electrons • The electrons responsible for the chemical properties of atoms are those in the outer energy level. Valence electrons – These are the electrons in the outer shell. They are the ones that do the bonding to other atoms. Core electrons -those in the shells below ... not the valence electrons

  11. Counting the Pieces Atomic Number (Z) • is the number of protons in that atom • determines type of atom. • all atoms of the same element have the same atomic number • located above the symbol in the periodic table • the same as the number of electrons in the neutral atom. • order of the elements in the periodic table

  12. Atomic mass Number (A) • Is the number of protons + neutrons. • A= Z + n • All the things with mass.

  13. Symbols A X Z 23 Na 11

  14. Symbols • Find the • number of protons • number of neutrons • number of electrons • Atomic number • Mass Number • Name 24 Na 11

  15. Examples 3 5 3 3 8 11 11 11 11 22 4 4 4 4 8 26 30 26 26 56

  16. Symbols • if an element has 78 electrons and 117 neutrons what is the • Atomic number • Mass number • number of protons • Complete symbol • Name

  17. Examples 6 7 6 6 13 54 77 54 54 131 11 13 11 11 24 8 7 8 8 15

  18. Example Write the atomic symbols for atoms with the following: A. 8 p+, 8 n, 8 e- ___________ B. 17p+, 20n, 17e- ___________ C. 47p+, 60 n, 47 e- ___________

  19. Homework • Handout • Due tomorrow

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