1. Chemistry of Life Unit 1 Lesson 5

2. Students will be able to:
Chemistry of Life
Students will be able to:
Describe the structure of atom and how atoms make up matter.
Understand the major types of chemical interactions.
Define the chemical reaction.
Key Vocabulary:
Atom, molecule, element, nucleus, electron, octet rule, ionic bond, covalent bond, polar, nonpolar, hydrogen bond, van der Waals interactions, chemical reaction.

3. Chemistry of Life
Do you ever think about your body and what is your body made of? You might think about different organs such as heart and brain that made up your body.
At the first place, our bodies and all other life forms, as well as the nonliving things is made up of atoms that organized to form larger structures which called molecules.

4. Let's demonstrate some chemistry basics.
Chemistry of Life
Actually, the simple interactions and combinations between atoms are what make life possible.
Everything including your feelings, is the consequence of chemical and electrical interactions between a huge number of nonliving atoms.
Let's demonstrate some chemistry basics.

5. Chemistry of Life
The Atom
All matter is made up of a mixture of substances called elements.
Elements cannot be broken down into another simpler substance under standard chemical reactions.
There are 92 naturally occurring element around us. The others have been cooked by the scientists inside the laboratory.
Inside of elements, you will find identical atoms.

6. The Atom Any atom consists of two regions:
Chemistry of Life
The Atom
Any atom consists of two regions:
The tiny nucleus, that is found in the center of the atom and comprises two kinds of subatomic particles. The positively charged protons and neutral, uncharged neutrons.
The larger region of the atom is the orbits of negatively charged electrons which spin around the nucleus.

7. Chemistry of Life
The Atom
The attraction forces between protons and electrons holds the atom together.
Most atoms in the periodic table contain all three types of subatomic particles except the hydrogen atom because it has one proton and one electron without neutrons.
The number of protons in the nucleus determines the kind of the element an atom is, while the number of electrons determines which kind of reactions the atom will undergo.

8. Chemistry of Life
The Atom
All living things on our planet are made up of atoms that are connected by various chemical bonds and organized into molecules.
Many atoms might form temporary, weak bonds or strong bonds with other atoms.
These two types of bonds hold molecules together and make temporary connections that are vital to our body, and to the existence of life.

9. Chemical bonding Why the atoms usually tend to form chemical bonds?
Chemistry of Life
Chemical bonding
Why the atoms usually tend to form chemical bonds?
Obviously, the atoms usually don't have enough electrons to fill their outermost shells, and they trying to reach the most stable state of energy.
The atoms become more stable when they reach the octet rule via holding eight valence electrons. If atoms don’t have this arrangement of valence electrons, they forming chemical bonds.
There are four types of chemical interactions: ionic, covalent, hydrogen bonds and van der Waals interactions.

10. Chemistry of Life
I. The ionic bond
The ionic bond is considered as a strong bond that require high energy to break down.
The atoms become more stable by gaining or losing electrons and form ions that make it energetically more stable.
When the atom donates an electron from its outer shell, it forms a positive ion called cation and when the atom accepts the electron, it forms negatively charged ion that known as anion.

11. Chemistry of Life
I. The ionic bond
Because the opposite charges attract, these positive and negative ions attract together and form the ionic bond.
The atoms bonds together in this type of bonds with the electron from one element staying mostly with the other element.

12. Chemistry of Life
I. The ionic bond
For example, in the sodium chloride molecule (NaCl), the sodium atom loses an electron to become a sodium cation, Na+ and the chlorine atom gain this electron to become chlorine anions. Anions are named by using the suffix “-ide”: for example, the chlorine anion Cl- is called chloride.

13. Chemistry of Life
I. The ionic bond
Certain ions such as sodium, potassium and calcium are referred to electrolytes in physiology.
These ions are essential for nervous system, muscle contractions and water balance in our bodies.
Many sports drinks and dietary supplements provide various ions to replace the loss of ions via sweating during workout.

14. Chemistry of Life
II. The covalent bond
The second type of strong chemical interaction between atoms is the covalent bond that considered as the most common and strongest form of chemical bonding in living organisms.
This type of bonds is formed by sharing electrons between two atoms rather than gaining or losing the electrons such as the bonds in carbon-based molecules.

15. Chemistry of Life
II. The covalent bond
For example, in the water molecule, each hydrogen atom shares one electron with the oxygen atom and the oxygen atom share two electrons (one electron to each hydrogen atom). The shared electrons divide their time between the oxygen and hydrogen atom giving each atom almost complete valence shell.

16. II. There are two basic types of covalent bonds:
Chemistry of Life
II. There are two basic types of covalent bonds:
Polar covalent bond in which the electrons are unequally shared between the two atoms of different elements.
In this type of covalent bonds, the electrons spend more much time close to one nucleus than to another nucleus.
As the result of this unequal distribution of the electrons, a slightly negative charge (δ–) and slightly positive charge (δ+) develop in the molecule.

17. II. There are two basic types of covalent bonds:
Chemistry of Life
II. There are two basic types of covalent bonds:
Polar covalent bond
In the previous example of water molecule, the oxygen atom is more electronegative than the hydrogen atom and attract the shared electrons more strongly, so the oxygen atom bears slightly negative charge and the hydrogen atom bears slightly positive charge.

18. Nonpolar covalent bond
Chemistry of Life
II. There are two basic types of covalent bonds:
Non-polar covalent bond in which the electrons are equally shared between the two atoms of the same elements or between atoms of different elements that have approximately the same electronegativity.
For example, the oxygen molecule is non- polar because the electrons spend equal time between the two atoms.
Nonpolar covalent bond

19. Nonpolar covalent bonds
Chemistry of Life
II. There are two basic types of covalent bonds:
Non-polar covalent bond
The methane molecule (CH4) is another example of the nonpolar molecule.
In this molecule the carbon atom shares four electrons -one to each hydrogen atom- and each hydrogen atom share one electron to the carbon atom.
The two elements are sharing electrons equally that create four nonpolar bonds.
Nonpolar covalent bonds

20. Chemistry of Life
III. The hydrogen bond
The hydrogen bond is relatively weak bond that don't require much energy to break.
It's an attraction that occur between positive and negative charge.
This bond is responsible for the unique properties of water and stabilize the DNA and protein structures so, without this kind of interaction, there is no life on earth.

21. Chemistry of Life
III. The hydrogen bond
Hydrogen bond exist when a polar covalent bond that containing hydrogen atom is formed.
Because the sharing electrons is pulled from the hydrogen, it will have a slightly positive charge.
This hydrogen atom will be easily attracted to a slightly negative neighboring charge that result in interaction between these opposite charges.

22. IV. The van der Waals interactions
Chemistry of Life
IV. The van der Waals interactions
Van der Waals forces, is a general term for any intermolecular interactions that do not include ionic or covalent bonds.
It is considered as a weak interaction between molecules.
They occur between polar covalent bonds and atoms in different molecules and they are vital to any biological system.

23. Chemistry of Life
Chemical Reaction
Any molecule found is a combination of two or more atoms.
For example, the oxygen in the air consists of two atoms connected by chemical bonds.
Another example that include different elements is the carbon dioxide compound which consists of carbon atom and two oxygen atoms.
The compound is the combination of two or more different atoms and usually have different properties from the atoms that form the compound.

24. Chemistry of Life
Chemical Reaction
Chemical reaction is the process in which chemical bonds between atoms are formed or broken in the molecule.
The substances that start a chemical reaction are called the reactants, and the molecules that produced as the result of chemical reaction are called the products.

25. Chemistry of Life
Chemical Reaction
Atoms of different elements come together to form compounds other than water and carbon dioxide molecules.
These large compounds interact and work together to form the basic life of the cell. So fundamentally, your body cells are made of compounds that are made from atoms.
Ionic and covalent bonds along with weak bonds such as hydrogen and van der Waals interactions play key roles in the chemistry of our cells and bodies.

26. Chemistry of Life
In the cell
In the DNA molecule, strong covalent bonds hold together the building blocks that make up the DNA strand.
The hydrogen bonds are also found in the DNA and hold together the two strands of the DNA forming a double helix.
Billions of chemical interactions holding the life in our bodies.
Hydrogen bond
Covalent bond

27. Chemistry of Life
Summary
Our bodies and all other life forms, as well as the nonliving things is made up of atoms that organized to form larger structures which called molecules.
All matter is made up of a mixture of substances called elements.
An atom is the smallest building block unit of matter that has all chemical properties of an element.
There are four types of chemical interactions: ionic, covalent, hydrogen bonds and van der Waals interactions.
Chemical reaction is the process in which chemical bonds between atoms are formed or broken in the molecule.