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Warm Up #1

Warm Up #1. Use a sheet of notebook paper to do your daily warm up. You will turn them in every few weeks! 175kg = _____ g What 2 parts make up the nucleus of an atom? What does the atomic number of an element indicate?

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Warm Up #1

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  1. Warm Up #1 Use a sheet of notebook paper to do your daily warm up. You will turn them in every few weeks! • 175kg = _____ g • What 2 parts make up the nucleus of an atom? • What does the atomic number of an element indicate? • What 2 things in an atom must be equal for the atom to be considered neutral?

  2. Why is Earth called the Blue Planet? • It’s covered mostly by water! Water is the most abundant compound in most living things! The human body is about 60-70% water! In order to understand life on Earth, we need to understand some of the basic properties of water!

  3. Properties of Water

  4. A Molecule of Water • Written as H2O 1 atom of Oxygen (O) 2 atoms of Hydrogen (H)

  5. Cohesion • Attraction of water molecules to each other • They stick together! Water can form multiple hydrogen bonds between molecules!

  6. Adhesion • Attraction of water molecules to other things • They stick to other things! This is why a meniscus forms(water molecules stick to the side of the graduated cylinder)!

  7. A. AdhesionB. Cohesion Adhesion! The water molecules are holding on to this blade of grass.

  8. A. AdhesionB. Cohesion Cohesion! Many insects can walk on water, because their weight is not large enough to break the bonds between water molecules.

  9. Adhesion & Cohesion Adhesion & Cohesion also make it possible for water to travel from the roots to the top of a plant!

  10. Polarity of Water • Although water is electrically neutral, it does exhibit polarity! • This means that a water molecule has 1 slightly negative end & 1 slightly positive end! The electrons in a water molecule crowd around the oxygen atom, giving it a negative charge & the hydrogen atoms become more positive.

  11. Polarity & Solubility • Solubility refers to the ability of a substance (solute) to dissolve in another substance (solvent) In a water/sugar solution, water is the solvent & sugar is the solute!

  12. When a solute is dissolved in a solvent, the solute breaks apart & chemically combines with the solvent molecules. In a salt/water solution, what is the solvent & what is the solute?

  13. Polarity & Solubility • “Like dissolves like” • Polar substances dissolve other polar substances. • Nonpolar substances dissolve other nonpolar substances. • Polar & nonpolar substances do not mix! What would happen if you poured oil into a glass of water? Is water polar or nonpolar? WATER IS A POLAR MOLECULE!

  14. This is what happens when oil & water get together. Is oil polar or nonpolar? Nonpolar! If we know water & oil don’t mix & that water is POLAR, oil must be NONPOLAR! Polar Nonpolar Not enough info.

  15. Some people add sugar to their coffee. Is sugar polar or nonpolar? Polar! We know sugar will dissolve in water, so sugar must be polar, just like water. Polar Nonpolar Not enough info.

  16. Some people add sugar to their coffee. Is coffee polar or nonpolar? Polar! Now we know that sugar is polar & that it will dissolve in coffee, so coffee must be polar! Polar Nonpolar Not enough info.

  17. Why did the white bear dissolve in water? Because it was polar!

  18. Why do we care about polarity & solubility? • Remember! Most of our body is made of water & dissolved substances! • Polarity & solubility play a large role in forming cell barriers (membranes). • These barriers decide what comes in & out of your cells! The environment inside & outside of a cell is mostly water (polar). The inner part of the cell membrane, however, is nonpolar.

  19. Do all substances that are put together chemically combine? NO!

  20. Mixtures • 2 or more substances in same place, but not chemically combined • Substances in a mixture keep their individual properties!

  21. Solutions • The dissolved material (solute) becomes evenly distributed through the entire liquid (solvent)

  22. Suspensions • Mixture of water & a non-dissolved material Mud is a suspension, because the dirt is not fully dissolved in the water!

  23. Blood… Mixture Solution Suspension Trick question! It’s a solution & a suspension! Blood is mostly water, but many substances are dissolved in it. However, the cells in blood remain in suspension!

  24. How many drops of water can you add to a penny before the water spills over? • Create your hypothesis! • You & your partner complete 3 trials each & take the average. • Answer the Qs!

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