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Atoms

Atoms. Unit 2 – Lecture 3. Atoms. smallest particle of an element that retains its chemical properties composed of subatomic particles protons (p + ), neutrons (n 0 ), & electrons (e - ) “sub-” = below, less than. Subatomic Particles. Types of Subatomic Particles

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Atoms

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  1. Atoms Unit 2 – Lecture 3

  2. Atoms • smallest particle of an element that retains its chemical properties • composed of subatomic particles • protons (p+), neutrons (n0), & electrons (e-) • “sub-” = below, less than

  3. Subatomic Particles Types of Subatomic Particles • [p+] – positively charged subatomic particle • found in the nucleus of an atom • relative mass = 1 amu [atomic mass unit] • [n0] – non-charged subatomic particle [neutral] • found in the nucleus of an atom • relative mass = slightly larger than 1 amu • new theories: [p+] + [e-] = [n0] ?

  4. Subatomic Particles – cont’d • [e-] – negatively charged subatomic particle • found outside of the nucleus in energy levels [aka e- clouds, e- shells, etc] • no relative mass • [actual mass is 1/1936th of 1 amu…] • Quarks? • theoretically = smaller particles that make up (p+), (n0), & (e-) • have their own branch of “theoretical physics”

  5. Discuss • Which subatomic particle is neutral? • Which describes a single particle of an element? • Which subatomic particle is negative? • Which subatomic particle may or may not exist? • Which is a single particle of a compound? • Which subatomic particle is positive?

  6. Elements • Elements are made of atoms. • atomic number – number of e- or p+ • chemical symbol – name of element • atomic mass – number of “nucleons” • nucleon = particle in the nucleus • ie, the mass of p+ plus mass of n0

  7. Elements – cont’d • Elements are found on the periodic table in their natural, neutral state • meaning, they’re neutral = same # of p+ & e -

  8. Discuss - Oxygen • atomic mass? • number of protons? • atomic number? • number of electrons? • chemical symbol? • number of neutrons?

  9. More Practice • An atom with 4 protons and 6 neutrons would: • have a mass of…? • have an atomic number of…? • have … electrons typically? • be which element?

  10. Writing Elements - Silver Write: • Chemical Symbol • Mass Number at the upper-left of the symbol • Atomic Number at the lower-left of the symbol • Charge [if applicable] at the upper-right hand corner NOT ALL OF THESE ARE NECESSARY Ag 108 +4 47

  11. Counting Particles • p+s = Atomic Number[17] • n0s = Atomic Mass – Atomic Number[35-17 = 18] • e-s = p+s[17] Cl 35 17

  12. Counting Particles – cont’d • if e-s differ • called ion • charge is different • more e-s [than normal] = more negative charge • less e-s [than normal] = more positive charge

  13. Counting Particles – cont’d • if n0s differ • called isotope • “iso-” = equal/same • same chem & phys properties • atomic mass on periodic table is average of isotopes • if p+s differ • is a different element

  14. Isotopes – Examples

  15. Different Atoms, Same Element • Allotrope – different natural/physical forms of an element • “allo-” = other/different • Ex. for Carbon: Graphite, Diamond, Buckminsterfullerenes [buckyballs]… • Ex. for Oxygen: [O2], Ozone [O3]

  16. Allotropes of Carbon • diamond • graphite • lonsdaleite • buckyballs [C60 – buckminsterfullerene] • C540 • C70 • “amorphous” carbon [not truly amorphous] • single-walled carbon nanotube / buckytube

  17. Allotropes of Oxygen

  18. Electron-Dot Models • p+s & n0s exist in the nucleus • e-s exist in electron/energy shells around the nucleus • “octet rule” - atoms will gain, lose, or share e-s to become chemically stable [8 e-s in valence shell] • valence shell = outer-most shell • e-s in valence shell = valence e-s

  19. Electron-Dot Models • Draw • Nucleus • Protons • Neutrons

  20. Electron-Dot Models – cont’d • Draw • Electrons • Electron Levels • *2* • up to 8…

  21. Discuss • Atoms are the smallest particle of • elements, compounds, homogeneous mixtures, heterogeneous mixtures • Which subatomic particle has a neutral charge? • protons, neutrons, electrons, quarks • What is the dense center of an atom called? • protium, nucleus, neutron core, core

  22. Discuss • Which property discerns atoms from one another? • atomic mass, mass number, atomic number, none of the above • Atomic Number is based on which property of atoms? • # of protons, # of electrons, # of neutrons, total # of particles

  23. Discuss • The total number of nucleons is • atomic mass, atomic number, nucleon count, state of matter • Atoms of an element with different number of neutrons are • allotropes, isotopes, megatopes, gigatropes • Which subatomic particles are not included in calculating Atomic Mass? • protons, neutrons, electrons, nucleons

  24. Discuss • How many neutrons are in Oxygen-16, which has an atomic number of 8? [# denotes mass] • 4, 6, 8, 10, 12, 14, 16 • How many neutrons are in Oxygen-18, which has an atomic number of 8? • 4, 6, 8, 10, 12, 14, 16 • Which subatomic particle has a positive charge? • Protons, Neutrons, Electrons, Quarks • How many e-s fit in an atom’s first electron level?

  25. Homework • Complete - page 13 - # of Atoms in a Formula w/s DO NOT COMPLETE GRAM FORMULA MASS w/s IN THE MIDDLE OF PAGE 13. - BOTTOM of pg 13-top of 14 Parts of An Atom [CHART]

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