Properties of matter elements compounds and bonding


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Properties of matter elements compounds and bonding

  1. 1. Properties of Matter, Elements, Compounds, and Bonding. 9/14
  2. 2. Chemical Properties. A chemical change pemanantly changes the conpound into another. Basic unit of matter is an atom Subatomic particles- protons (+), neutrons, and electrons (-)
  3. 3. Atoms Protons neutrons in the nucleus Electrons travel around the nucleus in orbits or clouds or levels of energy. Atom is neither positive or negative in charge - it is neutral. ION- An atom that has lost or gained an electron(s)
  4. 4. Identifying Elements Atomic number- number of protons The number of protons (atomic number) determines the identity of an element An element- only one type of atom Represented by a chemical symbol such as O for oxygen or Na for sodium CHNOPS- Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorous, Sodium  main elements of human body
  5. 5. Isotopes Atoms of the same element that have a different number of neutrons Many (not all) are unstable and break down, emitting energy – radioactive isotopes Used for determining the age of fossils, treatment of diseases, and even to sterilize food.
  6. 6. Chemical Compounds Compounds- Chemical combination of two or more elements  Represented by a chemical formula that indicated the elements in the compound and their proportions.
  7. 7. Chemical Bonding In order to become stable, an atom will either gain, lose, or share electrons. Each level can hold only a certain number of electrons. (2,8,8) Ionic, covalent, and polar covalent bond
  8. 8. Covalent Bonding Equal Sharing of electrons Each atom fills it’s outermost energy level Smallest particle of a compound is a molecule
  9. 9. Ionic Bonding An ionic bond forms when one atom gains electrons and the other loses electrons Ions are held together by their opposite charges Involves atoms of very different sizes
  10. 10. Chemical reactions The making or breaking of bonds is called a chemical reaction Reactants (chemicals that enter a reaction) & products (compounds that are produced) A chemical reaction is indicated by a chemical equation. Na (+) + Cl (-) ---> NaCl O2 + 2H2  2H2O
  11. 11. Polar Covalent The unequal sharing between two atoms (usually one much larger than the other) Creates slight charge on either side of the molecule.
  12. 12. Hydrogen bond Between hydrogen and another atom such as nitrogen or oxygen Weak attractive force that forms temporary, easily broken bonds
  13. 13. Water importance for living things Water has an unusual chemical structure We are over 70% water
  14. 14. Properties of water 1. less dense as a solid Found in all three states (solid, liquid and gass) on the earth
  15. 15. 2. Water is a good solvent. Many compounds dissolve in water. 3. Water is slow to heat and slow to cool. 4. water is cohesive – water molecules will attract other molecules 5. water is adhesive- water adheres to other molecules
  16. 16. Why? The bonds are covalent, but the sharing is unequal The water molecule carries a slight charge It is polar
  17. 17. Hydrogen Bonds The slight charge attracts other water molecules This forms weak temporary hydrogen bonds
  18. 18. As water changes state it adds or breaks apart hydrogen bonds. This slows changes in temperature
  19. 19. solvent Some hydogen bonds will pull strongly enough to break off a hydrogen ion H2O H(+) + OH (-) This will ionize a small portion of the water creating equal numbers of hydrogen and hydroxide ions solution (solute and solvent) NaCl  Na+ Cl -
  20. 20. In a liter of water only 0.0000001 m/l of water has ionized. (That’s 1x10 ^-7) (PH=7) PH stands for the percent of hydrogen ions in solution in relation to hydroxide ions More hydrogen ions are added the ph will go down (example hcl) If more hydroxide ions (OH) are added then the PH wil go up (example. NaOH)