Basic Chemistry: Atomic Structure, Elements, and Electron Behavior

all matter is made of?

elements, substances that cannot be broken down into something simpler

96% of living matter is made up of just what 4 elements?

1. carbon

2.oxygen

3. hydrogen

4. Nitrogen

Trace elements are required only in?

Minute quantities

Atom

the most basic unit of matter

Atoms are made up of?

subatomic particles

Protons

(positive charge) nucleus; mass=1

Neutrons

(neutral charge) nucleus; mass=1

Electrons

(negative charge) orbit around nucleus; mass=0

Atoms are neutral in charge; for normal atoms, protons, neutrons, and electron number are?

equal

An element's atomic number is the number of?

Protons in the nucleus

Atomic weight (mass number)

is the number of protons + neutrons in a element

some atoms of an element have more neutrons than normal these are called?

Isotopes

Some isootpes are unstable or radioactive, and their nuclei does what?

Decays spontaneously

The farther away an electron is from the nucleus,

the more potential energy it has

changes in this amount of potential energy can occur ONLY in?

steps or fixed amounts

electrons can change the electron shell they occupy ONlY by?

absorbing or losing energy

The first electron shell can hold NO MORE than 2 electrons and the second shell can hold up to?

8 electrons

The chemical behavior of an atom depends mostly on?

the number of electrons in its outermost shell, or valence shell

if the outermost electron shell is full, the atom is stable and WILL NOT

react with other atoms

Atoms will incomplete valence shells tend to interact with other atoms to....

become stable

A covalent bond occurs when?

A pair of valence electrons is shared between 2 atoms

Covalent Bonds

A very strong covalent bond

Electronegativity

a particular atom in a covalent bond has a stronger pull on the shared electrons than other atoms

if electrons are not shared equally, the bond is called?

Polar covalent

When they are not shared equally this results in..

an unequal distribution of charge among the atoms in the molecule

If electrons are not shared equally, the bond is called?

nonpolar covalent (H2)

When 1 atom is electronegative that it strips an electron completely away from another atom an

ionic bond has formed

The atom that gains the electron has a negative charge and is called an

Anion

The atom that loses the electron has a positive charge and is called a

Cation

A hydrogen bond forms between a?

hydrogen atom of one molecule and a more electronegative atom in a different molecule

Hydrogen Bonds

-They are easily broken and reformed

-They are very important biologically

-Holds water molecules together

-connects stands of the DNA double helix

-protein folding

Decompositions

reactions break chemical bonds and release chemical energy (exergonic, catabolic)

Synthesis

reactions form chemical bonds and must absorb energy to occur

Inorganic molecules

- generally do not contain C (except CO2)

-usually smaller

-usually dissolve in water or react with water to release ions

-include oxygen, carbon dioxide, water, salts, acids and bases

organic molecules

-contain C and H

-usually larger

- include carbohydrates , lipids, proteins, and nucleic acids

Inorganic molecules CO2

Carbon Dioxide

-reacts with water to from carbonic acid

-is removed from the body via respiration

Inorganic molecules O

Oxygen

required for cellular respiration

Water is a polar molecule that

demonstrates hydrogen bonding and very unique

Characteristics of a polar molecule

-excellent solvent

-provides site for most metabolic reactions

-absorbs and releases heat very slowly

-provides and excellent cooling mechanism

-major component of mucus and other lubricating fluids

The dissociation of water molecules leads to

acidic and basic conditions that affect living organisms and chemical reactions

Water dissociates into?

hydroxide ion (OH-1) and a hydrogen ion (h+)

An acidic solution is one that has more

H+ than OH-

A base is a substance that reduces the?

H+ concentration of a solution

solutions with a higher OH concentration are?

Basic

when ion concentration are equal the solution is?

neutral

Neutral?

7 pH

Acidic?

PH is less than 7

Basic?

PH is greater than 7

Numbers on the scale denote a?

tenfold

Buffer

a substance that minimizes a change in PH

A buffer functions by

donating H+ when needed and accepting H+ when in excess

The carbonic acid buffering system helps maintain

blood PH around 7.4

salts are held together by

ionic bonds

Salts dissociate into ions when

dissolved into water

Salts are abundant in

body fluids

Salts are sources of

necessary ions

Carbohydrates contain

H,C, and O usually in some multiple of CH2O

The carbohydrate monomer is the

monosaccharide

The primary function of a carbohydrates in humans is that

they serve as our main energy source

The breakdown of glucose during cellular respiration releases the stored chemical energy that is used to make what

ATP

The atoms that compose them are often rearranged to make other..

organic compounds

what can be used to link together two monosaccharides and what does it form

dehydration reaction; disaccharide

hundreds to thousands of monosaccharides can link to form large carbohydrates called

polysaccharides

what is the main polysaccharide made by the human body

glycogen

what is stored mainly in the liver and skeletal tissue

glycogen

Lipids

mostly made of long hydrocarbon chains (C and H) with the occasional oxygen atom