Elements, Atoms, and Ions


Published on

Published in: Education
  • Be the first to comment

  • Be the first to like this

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Elements, Atoms, and Ions

  1. 1. Elements, Atoms, and Ions
  2. 2. Elements The most abundant elements are: C, H, O, N (P, S) Trace elements necessary for human function in small amounts include: Cu, I, F
  3. 3. Elements & their names/symbols Element names reflect either their properties, the city of their discovery, or are given in honor of a scientist (not necessarily the discoverer of the element) Symbols always start with a capital letter. If it has more than one letter, all other letters are in lower case The first letter of the element symbol is the first letter of the element name. However it may either be based on its English or Latin origins (ex: Sodium is Na for natrium.
  4. 4. Atoms & Compounds Dalton’s Atomic  Elements are pure Theory is a substances compilation of the  Mixtures of pure observations of substances are called scientists about atoms compounds in the 1800s.  Proportions in Those observations compounds are fixed include: (the law of constant composition)
  5. 5. Dalton’s Atomic Theory Elements are made of tiny indivisible particles called atoms All atoms of a given element are identical Atoms of an element are different from the atoms of a different element Atoms of one element can combine in fixed ratios with atoms from another element to form compounds Atoms are neither created nor destroyed in chemical reactions, but are simply recombined
  6. 6. John Dalton Published a periodic table of elements based on atomic weights in 1803 He was interested in predicting the behaviors of substances based on their properties as organized in his table His accomplishments include discoveries in chemistry, meteorology, & medicine (color blindness)
  7. 7. John Dalton’s Atomic Theory http://www.youtube.com/watch?v=HFF- 2wyyTKc
  8. 8. Compounds Chemical formulas represent the types and numbers of atoms in a compound. Numbers are written as subscripts to the right of each element symbol, representing the number of atoms of that element in the compound NO2
  9. 9. Atomic Structure Atoms consist of three particles: protons, neutrons, and electrons Protons and neutrons make up the center known as the nucleus. Protons have a positive charge while neutrons are electrically neutral Electrons circle around the nucleus in energy levels (aka shells) and have a negative charge
  10. 10. Evolution of the Atomic Model The Greeks named the atom after the word ‘atomos’ meaning indivisible
  11. 11. Evolution of the Atomic ModelThomson’s plum pudding model based on the cathode ray tube experiments in the late 1800s (1897) showed that there were negatively charged particles in the atom
  12. 12. Cathode Ray Experiment http://www.youtube.com/watch?v=JwdGF ZA3WOs http://www.youtube.com/watch?v=RW_zf KOU9uM
  13. 13. Evolution of the Atomic Model Rutherford and the Plum pudding vs. gold foil experiment Rutherford’s model (1911) showed that those negatively charged particles were located outside a dense positively charged center he termed the nucleus
  14. 14. Gold Foil Experiment http://www.youtube.com/watch?v=5pZj0u _XMbc http://www.youtube.com/watch?v=bSEO OMs5VNU
  15. 15. Evolution of the Atomic Model Bohr’s model (1913) aka the Rutherford- Bohr model gave more details as to the location of electrons around the nucleus Work based on line emission spectra It showed the electrons in circular paths around the nucleus called orbits
  16. 16. Evolution of the Atomic ModelModern theory of atomic structure Broglie and Shrodinger (1924, 1926) showed the electrons show some wave like behavior and we can predict their location around the nucleus in terms of probabilities.
  17. 17. Modern Atomic Theory From this stemmed the idea of electrons arranged in orbitals at varying distances from the nucleus
  18. 18. Isotopes Two atoms of the same element with same number of protons and electrons but differing numbers of neutrons (differing mass numbers) Because the name of an element is determined by the number of protons (atomic number)
  19. 19. Mass & Atomic NumbersMass number (# of p + n) –Atomic number (# of p)# of neutrons in the atom
  20. 20. The Periodic Table Periods are the horizontal rows Groups (families) are the vertical columns
  21. 21. Metals, Nonmetals, & MetalloidsMetals: Non Metals: Shiny  Are none of these Solid (except Hg) things Good conductors of heat Metalloids: Good conductors of  aka semiconductors electricity  Have some metallic Malleable properties to some Ductile degree in some situations
  22. 22. Major groups of the P.T. Main element groups (tall columns) Alkali metals (AM) +1 Alkaline earth metals (AEM) +2 Halogens (halo=salt) -1 Noble gases (inert) no ions formed Transition metals ion formation varies Lanthanide/actinide series (radioactive)
  23. 23. Main Element Groups All other main element groups go by the name of the first element in the group (ex: Boron family)
  24. 24. Periodic Table History Mendeleev is credited with putting together the first periodic table in the 1860s Mendeleev’s table was organized using atomic weights of elements It was an important breakthrough because he was able to predict the properties of elements not yet discovered at the time
  25. 25. Periodic Table History Mendeleev’s table revealed patterns in valence electron #s and properties of elements within the same group (family) http://www.youtube.c om/watch?v=inwaqkj a6TE
  26. 26. Periodic Table History Henry Moseley in 1914 was able to use modern technology to determine that the atomic number was a better way of organizing the periodic table first created by Mendeleev. Organizing it this way increased the progressive and predictive capabilities of the table Our modern day periodic table is organized by atomic number
  27. 27. Diatomics Some elements exist in pairs of atoms called diatomic molecules They include (and you need to memorize) the following: H2 N2 O2 F2 Cl2 Br2 I2
  28. 28. Atoms vs. Ions Atoms are neutral overall but can lose/gain electrons to form ions (atoms with a charge) You can predict ion formation by using the periodic table Elements in the left hand columns lose electrons to form positive ions (cations) Elements in the right hand columns gain electrons to form negative ions (anions)
  29. 29. Ionic Compounds Are formed when negatively and positively charged ions are attracted to each other in order to regain a neutral charge overall. The ions bond in numbers that will allow for a net charge of zero (neutral) or they won’t bond at all For example: F- and H+ form the ionic compound HF Ca+2 and Br- form the compound CaBr2