“I’ll believe it when I see it…”What have you learned about in science that is either too small or too big to fully perceive with your senses?

What have you learned about in science that is either too small or too big to fully perceive with your senses?

Examples: water molecule, earth’s rotation, water cycle, germs, photosynthesis, plate tectonics, lunar tides

“I’ll believe it when I see it…”

The Biochemical Basis of Life

Essential Questions:— What are atoms and what they are composed of?— How do the components of an atom vary?— How do atoms interact with each other?

Why learn about atoms?

• How can we eat such different kinds of animals and plants and then use those materials to construct or our bodies?

• Plants don't eat as we do. How do they construct themselves?

• Why doesn't all the water on earth simply disappear through evaporation?

Your turn! What do you know about atoms?

• What do they look like?

• What do they look like?

• Where are they?

• Are they in solids? Are they in liquids?

• Are they alive?

• Are they in dead things?

Your turn! What do you know about atoms?

Scale: micro to macro

Atoms

An atom is the smallest unit of an element that has all of the characteristic properties of that element.

• Everything living and non-living is made of atoms.

• An individual atom of a substance, like gold, has all the characteristics of that substance.

• A gold atom is made up of smaller components called protons, neutrons, and electrons. By themselves, these subunits do not have the properties of gold.

Atomic Structure

# protons = # neutrons

Atomic Mass = # protons + # neutrons

Atomic Number = # protons

Component Charge Location MassNeutron No charge (0) Nucleus = mass of proton

Proton Positive (+) Nucleus = mass of neutron

Electron Negative (-) Energy levels/Surrounding Shells

= 0 (very light)

Valence electrons

– Electrons travel around the nucleus in regions called energy levels

– There are 2 electrons in the innermost energy level or shell

– Valence electrons are the electrons that travel in the outermost energy level or shell

– Atoms are in a stable “happy” state when they have a complete outer shell (2, 8, or 18 electrons)

Your Turn!How many Valence Electrons are in each atom?

Your Turn!How many Valence Electrons are in each atom?

3 54

Periodic Table of Elements …a crash course

An element is the most simple chemical substance. It is composed of one type of atom.

“…‘Our schoolchildren, some as young as the fourth grade, are being exposed to this deadly element in their science classes,’ said Tricia Montcalm, president of the Grand Rapids Parents Association.”

Periodic Table of Elements …a crash course

An element is the most simple chemical substance. It is composed of one type of atom.

# protons = # electrons(+) = (-)

Elements have no charge

Elements below and to the left of the purple “staircase” line on the table are metals (except for H).

Elements above and to the right of the purple “staircase” line on the table are non-metals.

Element Column # valence electrons

Hydrogen 1 1

Carbon 14 4

Oxygen 16 6

Neon* 18 8

The column number gives the number of valence electrons in the element:

Patterns in the Periodic TableElement Column # valence

electronsHydrogen 1 1

Carbon 14 4

Oxygen 16 6

Neon * 18 8

Scale – from micro to macroHow do atoms interact to form the components of our bodies and the earth?

Scale – from micro to macroHow do atoms interact to form the components of our bodies and the earth?

Bonds!

Ionic Bonds1. Ionic bonding occurs between

metals and non-metals.

2. Atoms held together by ionic bonds form a compound.

3. The opposite charges of the elements (ions) attract.

4. Atoms are in a stable “happy” state when they have a complete outer shell of valence electrons (2, 8, or 18).

5. If atoms have 1 or 2 electrons too few or too many, they gain or lose electronsin order to achieve a complete outer shell of valence electrons.

Covalent Bonds1. Ionic bonding occurs between non-metals.

2. Atoms held together by covalent bonds form a molecule (like water!).

3. Covalent bonds are the most common in Biology.

4. Atoms are in a stable “happy” state when they have a complete outer shell (2, 8, or 18).

5. If atoms have more than 3 electrons too few or too many, they share electrons in order to achieve a complete outer shell of valence electrons.

6. Sharing electrons is easier because it takes less energy than fully gaining or losing them.

IsotopesIsotopes are atoms of the same element that contain different numbers of neutrons.

Your turn!How many neutrons are in each isotope of Carbon?

IsotopesIsotopes are atoms of the same element that contain different numbers of neutrons.

Your turn!How many neutrons are in each isotope of Carbon?

6 7 8

Bonds at a glance…http://www.youtube.com/watch?v=QqjcCvzWwww

Your turn!1. What type of bonding occurs when electrons are

transferred (gained or lost)?

2. What type of bonding occurs when more electrons are shared?

3. What part of the atom is responsible for how an atom interacts with another atom?

4. In what case will an atom not react to another atom?

Bonds at a glance…http://www.youtube.com/watch?v=QqjcCvzWwww

Your turn!1. What type of bonding occurs when electrons are transferred

(gained or lost)? Ionic bonding

2. What type of bonding occurs when more electrons are shared? Covalent bonding

3. What part of the atom is responsible for how an atom interacts with another atom? Electrons (e-)

4. In what case will an atom not react to another atom?When the valence electron shell is complete on its own, or when it is complete because it is bonded (ionic or covalent) with 1 or more atoms)

Case Study: Affect of Carbon Monoxide on the Function of Hemoglobin

• Why is it important that these O2 and CO2 bond well to Iron atoms in the heme molecules?

• How does Oxygen & Carbon Dioxide bond to the Iron in your blood cells?

Question/Problem: Why is Carbon Monoxide deadly?

1. Compare CO2 and CO. Which is more stable? How do you know?Record your observation in your notes

• Hint: How many electrons does Carbon need to have a complete outer shell?• Hint: Are atoms stable if they have do not have a complete outer shell? What

do atoms do when they do not have a complete outer shell?

2. What do you think will happen if you breathe in Carbon Monoxide instead of Carbon Dioxide?

Record your hypothesis in your notes, make sure to state something about bonding.

Experiment & Conclusions• Background:

– http://www.youtube.com/watch?v=wKIrbq2pWvw

• Conclusions:1.Why is CO more unstable than CO2?

• Carbon does not have its valence shell full.

2.What does that instability mean for the hemoglobin?• CO will bond to heme more quickly and tightly. But won’t let go to let

normal O2 and CO2 in.

3.Why are bonding properties of atoms, compounds and molecules important?

• In this example, your body needs to get Oxygen to cells and get rid of CO2 properly. If not, the cells and eventually the body will die.