Atoms, Molecules, and Life

1. Atoms, Molecules, and Life

4. Most Elements Molecular (a) In hydrogen gas, one electron from each hydrogen atom is shared, forming a single covalent bond. The resulting molecule of hydrogen gas is represented as H–H or H 2 . (b) In oxygen gas, two oxygen atoms share four electrons, forming a double bond (O=O or O 2 ).

5. Ionic Bonding in NaCl Sodium ion #e=#p-1 Chlorine ion #e=#p+1 Negative charge Positive charge ± + – ± + ± + ± + ± + ± + ± + ± + – – – – – – ± + – – – ± + – ± + ± + ± + ± + ± + ± + ± + – – – – – – ± + – – – – – – – – – – ± + – ± + ± + ± + ± + ± + ± + ± + – – – – – – ± + – – – – Sodium #e=2+8+1=#p ± + – ± + ± + ± + ± + ± + ± + ± + – – – – – – ± + – – – – – – – – – – Chlorine #e=2+8+7=#p – – – Electron Completely Transferred

8. Water Molecule H 2 O Oxygen Hydrogens H H O

10. Bonding Patterns of Common Atoms Sulfur Phosphorus Oxygen Nitrogen Carbon Hydrogen

13. Hydrogen Bonds O O H H H H + + + – – + + Hydrogen Bonds Water molecules carry slight charges Electrons favor O over H Hydrogen bonds form between O of one and H of another Not a “REAL” bond!!! No transfer of electrons!

14. Hydrogen Bonds Hydrogen bonds are like two children holding very-slippery hands. The bonds constantly break and reform

15. NaCl Dissolved by Water NaCl is ionicly bonded Water is polar and charged O sticks to Na + H sticks to Cl -

17. Cohesion among Water Molecules

18. The pH Scale Neutral pH + = pOH – Increasingly Acidic pH + > pOH – Increasingly Basic pH + < pOH – 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -13 -14 Lemon Juice Lime Juice Stomach Acid Coffee Urine Water Blood Sea Water Baking Soda Bleach Ammonia Oven Cleaner

23. Water molecules spread apart slightly during the freezing process

26. The End