Atoms and Molecules


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Atoms and Molecules

  1. 1. Do NOT make an ATOM an ION unless it tells you too! THIS MEANS- Do NOT make an ATOM stable unless it tells you to do so . To determine the charge of a picture of an atom look at the number of protons and electrons in the picture and determine the charge. (Examples are on the next slide.)
  2. 2. Review: What is the charge of this ATOM ? Just use the number of protons and electrons that are given .
  3. 3. What is the charge of this ATOM? Just use the number of protons and electrons that are given. -2
  4. 4. We will discuss: Chemical Symbol Atoms Elements Bonds Compounds Molecules Chemical Formulas Endothermic Reactions Exothermic Reactions
  5. 5. All matter is made of _____________. <ul><li>Atoms </li></ul>Why would an atom combine with other atoms? To make the atom stable When an atom combines with another atom, this forms a ______________________? Molecule
  6. 6. <ul><li>When atoms are joined together, they form a </li></ul><ul><li>_____BOND______. </li></ul><ul><li>Atoms bond together for a very simple reason: atoms like to have full valence shells . (8 electrons) </li></ul><ul><li>Atoms will share, give away, or gain electrons when forming a bond. </li></ul><ul><li>Substances in which 2 or more elements have bonded together form a material with unique chemical properties. </li></ul><ul><li>Example : water - 2 Hydrogen atoms bonded to 1 Oxygen atom. H2O </li></ul>
  7. 7. 6 C 12 Chemical Symbol
  8. 8. Molecules <ul><li>Are made of ______________ that have been joined together. </li></ul>ATOMS
  9. 9. Molecules form when atoms join Element Compound There are two types of molecules
  10. 10. Element Molecule <ul><li>Element </li></ul><ul><ul><li>If a substance has two or more of the same atoms it is a molecule that is an Element </li></ul></ul><ul><ul><li>Ex. O (the oxygen we breathe) is made out of two oxygen atoms </li></ul></ul><ul><ul><li>Other examples of Element Molecules: </li></ul></ul><ul><ul><li>H N </li></ul></ul><ul><ul><li>O </li></ul></ul>2 2 3 3
  11. 11. Molecules Element H 2 If all atoms in a molecule are alike, then the molecule is classified as an _______________. ELEMENT
  12. 12. Molecules form when atoms join Compound The other type of molecule is a compound. Do you think that the atoms joined together in a compound are all the same? NO! The atoms are different.
  13. 13. Compound Molecules <ul><li>A combination of two or more different elements (atoms) </li></ul><ul><li>Examples: </li></ul><ul><ul><li>1 Na atom + 1 Cl atom = the compound NaCl </li></ul></ul><ul><ul><li>2 H atoms + 1 O atom = the compound H O </li></ul></ul><ul><li>The examples above are compounds because the molecule is made out of _____________ atoms. </li></ul>2 DIFFERENT
  14. 14. Energy in Chemical Reactions <ul><li>Often energy is released or absorbed in chemical reactions. </li></ul><ul><li>Where does the energy come from?? Bonds break or form from electrons being lost or gained. </li></ul><ul><li>Energy is released when there is less energy in the products than the reactants. This is called an EXOTHERMIC reaction. </li></ul><ul><li>If energy is absorbed there is less energy in the reactants than the products. This is called an ENDOTHERMIC reaction. </li></ul><ul><li>Exo = out Endo= in </li></ul>
  15. 15. Chemical Formulas- represent a molecule O C O The chemical formula of this model is CO 2
  16. 16. CO <ul><li>Chemical Formula </li></ul>2 C Chemical Symbol
  17. 17. The Chemical Formula use symbols and numbers called subscripts to show the elements and number of atoms that make up the molecule. <ul><li>H O </li></ul>2 Chemical Symbols Subscript Note: there are 2 hydrogen atoms and 1 oxygen atom. The one behind the O is imaginary. How many atoms are there? _____ 3
  18. 18. <ul><li>H O </li></ul><ul><li>Tells Us: </li></ul><ul><li>There are ______ atoms of hydrogen and _____ atoms of oxygen. </li></ul><ul><li>The name of the elements which are ____________ and ______________. </li></ul>2 2 1 Hydrogen Oxygen
  19. 19. CO represents? Co represents? Fe O represents? 2 3 1 atom of carbon and 1 atom of oxygen 1 atom of cobalt 2 iron atoms and 3 oxygen atoms
  20. 20. Chemical Formulas cont. <ul><li>Writing chemical formulas: </li></ul><ul><ul><li>Follow right to left pattern on the Periodic Table of Elements </li></ul></ul><ul><ul><ul><li>Ex. NaCl sodium is a metal located on the far left and Cl is located farther to the right </li></ul></ul></ul><ul><ul><ul><li>Therefore, the formula is written as NaCl instead of ClNa </li></ul></ul></ul>
  21. 21. If a molecule is made out of one type of atom, it is called <ul><li>A. Element </li></ul>
  22. 22. If a molecule is made out of different types of atoms it is? <ul><li>B. Compound </li></ul>
  23. 23. Chemical Equations <ul><li>Chemical equation tells about a chemical reaction. </li></ul><ul><li>It shows the substances we start with. </li></ul><ul><li>It shows the new substances that are formed. </li></ul>