M1A: Topic 3 - Chemistry of Life

What is an Atom?

The smallest unit of matter composed of protons, neutrons, and electrons

What are elements?

Types of atoms with different properties

What is the outer most shell called?

Valence shell

Is H stable with two electrons on the outermost shell?

Yes

When are elements the most stable?

When they have 8 electrons in the outermost shell

What are the basic building blocks of life?

C, H, O, N, P, S

When do chemical bonds happen?

When two or more atoms share or transfer electrons

What is the Octet rule?

A full outershell with 8 electrons = stable

They either share electrons with another atom OR they donate/receive unused electrons to/from another atom

What are Ionic bonds?

transfer of electrons (they are strong bonds)

What are Covalent bonds?

Two or more atoms share electrons (they are strong bonds)

What are hydrogen bonds?

Bond between hydrogen and another atom (weak bonds!) (*opposites attract*) bonds between slightly pos H and slightly negative H

Polar Covalent

When electrons are unequally shared

Nonpolar Covalent

When electrons are equally shared

What is pH?

The concentration of hydrogen ions (H+) in a solution

Acid

low pH = high H+ concentration

Base

high pH = low H+ concentration

Neutral

equal H+ to - OH

*Every step on the pH scale represents a 10X increase in H+ ions*

Just a reminder :)

What is the pH for blood?

7.4

What is the pH of stomach?

1-2 pH

What happens when pH gets out of “normal”

Buffer (prevents drastic changes in pH by absorbing or releasing extra H+ ions)