Transcription

1 Properties of Atoms Watch: Write down and define the following vocabulary words (you may use ch. 2.1 of your book or i-pad) there are 8 words, assign 4 words to each partner everyone is responsible for definitions, so make sure you know each word (write down notes) Atom: Molecule: Compound: Ion Cation Anion Ionic bond: Covalent bond:

2 Properties of Atoms

3 Properties of atoms Review energy levels: What is the electron energy level rule? 2-8-8=2 electrons in the first orbital, 8 in the second and 8 in the third (for many atoms) What makes a stable, non-reactive atom? Is Oxygen stable by itself? Why or why not?

4 Properties of Water

5 Water: 4#covalent_bond_hydrogen_animation Steps to show the covalent bond between H and O: 1) Pick a different color or different shading to draw your hydrogen circle and atomic particles. 2) Use the new color to draw a circle around one of Oxygen s outer electrons 3) Draw another Hydrogen circle around another nearby Oxygen outer electron. 4) Now add Hydrogen s electron next to each of the oxygen electrons.

6 Water: 4#covalent_bond_hydrogen_animation Water molecule formation is an example of a covalent bond. Now use your i-pad to find an example of an ionic bond Explain the difference between covalent bonds and ionic bonds to your partner:

7 Properties of Water Water is the universal solvent. The reason water has that power to dissolve is because of its charge. The oxygen side of water is negatively charged because the protons in oxygen's nucleus pulls the shared H electrons closer to the oxygen atom. The protons in the two hydrogen atoms are more exposed-the hydrogen side of water is positively charged. (source: SRP)

8 Molecular Structure of Water Review chemistry vocabulary: 1. Identify the type of bond formed between Oxygen and Hydrogen 2. When oxygen shares the H electrons, what charge does it have (toward opposite end of water)? 3. If oxygen were to completely gain electrons, would it be an anion or cation? 4. If hydrogen donates an electron instead of sharing electrons, would it be an anion or cation?

9 Life depends on hydrogen bonds + H _ O H + in water. Water is a polar molecule. Water pulls on things that are electrically charged. Magnets have north & south poles. Polar molecules have positive and negative charged poles Nonpolar molecules do not have charged regions. Example: lipids/fats are nonpolar Hydrogen bonds form between slightly positive hydrogen atoms and slightly negative atoms.

10 Hydrogen bonds are responsible important properties of water. high specific heat Low density solid formation (ice) cohesion adhesion

11 Hydrogen bonds are responsible for three important properties of water. high specific heat-it takes a lot of heat energy to break hydrogen bonds of water. It takes a long time for water to get warm enough to separate and turn into water vapor. Taking a long time to change temperature helps us maintain homeostasis!

12 Hydrogen bonds are responsible for three important properties of water. Low density solid-ice floats on water because it is lighter than water or less dense. Most substances become more dense as they change to solid, but water forms hexagonal crystals as it freezes that keeps the molecules surface area large and light instead of dense and compact.

13 Hydrogen bonds and Properties of water. Cohesion-same substances sticking together-attraction of water to other water molecules. Creates surface tension. Adhesion-sticking to other stuff Compare: dyed water on left sticks or adheres to stuff like tubes much easier than mercury on the right

14 Many compounds dissolve in water. REVIEW: A solution is formed when one substance dissolves in another. A solution is a homogeneous mixture (remember KOOLAID?) Solvents like water dissolve other substances like charged particles and solids. Solutes are often solids and/or charged particles dissolved by solvent. (sugar, salt etc.) solution

15 Properties of Water The Universal Solvent-Example of how water solvent dissolves solute (salt/nacl) : Since unlike charges attract, the negative end of water will be attracted to the positive sodium ion. The positive end of water will be attracted to the negative chloride ion. Since water is always in motion, it will pull on the ionic compound and move the ions away from each other. This dissolves the ionic compound. (source SRP)

16 Molecular Structure of Water A detailed look at the Molecular Structure as it relates to ph: Normally, shared Electrons surround the molecule, which has no overall charge.

17 ph Scale ph is a measure of how acid or alkaline (basic) a solution or substance is. This scale has numbers that range from 0 to on the ph scale represents a neutral ph (neither acidic or basic). Values less than 7 indicate acidity and values greater than 7 indicate alkalinity or basic.

18 Basic ph When a base is poured into water, it gives up OH - ions (hydroxide) to the water and removes H+ Hydroxide ions have an extra electron=negatively charged. Positive Hydrogen ions are removed from solution because of the attraction to the OH -. low H + concentration ph greater than 7 bile ph between 8 and 9 more basic

19 Acid ph When an acid is poured into water, it gives up H + ions (hydrogen) to the water. A hydrogen ion is a single hydrogen nucleus with a positive charge (it is missing one electron). high H + concentration ph less than 7 stomach acid ph between 1 and 3 more acidic

20 A neutral solution has a ph of 7. pure water ph 7

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