Oxygen (64%), Carbon (185%), Hydrogen (9.5%), and Nitrogen (3%). The other 4% includes calcium, phosphorous, and potassium.
What are all living things made of?
What are protons, neutrons, and electrons?
Protons are +, Neutrons are neutral, and Electrons are -.Electrons don't weigh anything.
What is the nucleus made of?
Protons and Neutrons.
What is an ion?
When an atom has an electrical charge due to an uneven number of protons and electrons.
The number of protons an atom has.
The number of protons plus neutrons.
What are isotopes?
The members of the same element with different weights due to a different number of neutrons.
What makes isotopes radioactive?
The extra neutrons are expelled from the nucleus which creates radiation.
Why does exposure to radioactivity cause damage to living cells?
As subatomic particles are ejected, they cross cell membranes.
How does our body deal with minor exposure?
Cellular repair mechanism.
Why do we use radiation as a therapy for cancer?
Free radicals can be targeted.
What is the most important subatomic particle in determining how and if two atoms can bond to each other?
How many electrons can fit in the intermost shell of an atom?
How many electrons can fit in the outermost shell of an atom?
What happens when the outer shell is full?
The atom won't bond to other atoms.
What is the goal of atoms bonding?
To fill their outer electron shell.
Only happens if one atom has an almost empty outer electron shell and the other atom has an almost full electron shell. The atom with the almost empty shell donates electrons to the almost full one.
When one atom donates electrons what happens?
It becomes a positive ion.
What happens to the atom it was donated to?
It becomes a negative ion.
When two or more atoms are near each other and require electrons in order to fill their outer shell. They share electrons. The atoms overlap their orbits and pool together their electrons.
What is the difference between polar and nonpolar covalent bonds?
Nonpolar: Electrons that are shared equally. Polar: The unqual sharing of electrons.
It can only happen if a polar covalent bond has already occurred. This is the unequally sharing of electrons that puts weak positive and negative charges on another.
What are all interactions between molecules based on?
What properties make it deal ideal for a basis of all living cells?
Hydrophilic-molecules attracted to water. Hydrophobic-molecules not attracted to water. Water is a solvent. Cohesion Adhesion Surface Tension High heat capacity-hydrogen bonds hold the molecules together Lower density when frozen
Which ions contribute to the pH of a solution?
H+ and OH-
Something added to water that increases H+ ions in the solution.
Something added to water that removes H+ ions from a solution.
Acidic: 0-6.9 Neutral: 7 Basic: 7.1-14
How do cells and living organisms prevent the pH from fluctuating?
Buffers-chemicals that prevent pH changes.
How do buffers work?
Releasing H+ when needed and absorbing H+ when needed.