CH.2 CHEMISTRY: THE STUDY OF INTERACTIONS OF ATOMS & MOLECULES

Matter

anything that occupies space and has mass

* solid
* liquid
* gas
* composed of elements

Energy

Capacity to do work or move matter

What are various forms of energies?

* chemical
* electrical
* mechanical

Chemical energy is

stored in bonds between atoms

Electrical energy:

movement of charged particles

Mechanical energy:

physical movement

Energy can change forms; most of the time it’s ____.

heat

Chemical energy from food is converted into bonds in

ATP (adenosine triphosphate)

ATP (adenosine triphosphate) is

• a high-energy molecule used by our cells

• Modified Nucleotide

Element

Simplest chemical substance with unique chemical properties

There are __ elements in nature

92

There are __ elements in humans

24

What are 4 most common in humans? (96%)

* hydrogen
* oxygen
* carbon
* nitrogen

What are the building blocks of elements?

atoms are the building blocks of elements

What are the simplest chemical substance with unique chemical properties?

Atoms

What are the characteristics of atoms?

\
* Smallest unit in chemical reactions
* Smallest structural unit in our bodies
* Non-Living

Atoms are composed of subatomic particles that differ in:

\
* Mass
* Charge
* Position

Proton

* Positive charge
* Mass is one atomic mass unit (amu)/dalton
* Located in atomic nucleus

Neutron

No charge; 1 amu; nucleus

Electron

* Negative charge
* No significant mass
* Orbits around nucleus

Nucleus

* Inner core
* Tightly bound protons & neutrons
* Positively charged

Electron Cloud

* Outer region
* Orbiting electrons (in orbitals, shells, clouds)
* Negatively charged

The overall charge of the atom is

neutral; the # protons = # electrons

The number of valence electrons affects…?

\
atomic reactivity

Atomic reactivity is stable if..?

valence is full

What does it mean when valence is full?

outermost occupied orbital is filled and is a noble gas (the rightmost elements on the table of elements)

What does it mean for the atomic reactivity to be reactive/unstable?

it means it has an incomplete valence (the outermost occupied orbital is not filled)

Atoms can:

\
* Gain/lose/share electrons
* Decay (e.g. Radioactive Isotopes)
* Protons are NEVER naturally lost or gained

Atomic number can

• Gain/lose/share electrons

• Decay (e.g. Radioactive Isotopes)

  • Protons are NEVER naturally lost or gained

Mass Number equation

Protons + neutrons

Neutron equation

Mass number– atomic number

Atomic symbol

The letter(s) used to represent atoms of the same element

CHEMICAL BONDS

\
* Join atoms by *valence electrons*
* Result in molecules, compounds
* Electrons gained, lost or shared to fill valence (or reach stability)

What are the three types of chemical bonds?

\
* Ionic or Electrovalent
* Covalent
* Hydrogen

IONIC BONDS

Transfer of electrons between atoms

Cation

Atoms that LOSE electrons have a net positive charge

Anion

Atoms that GAIN electrons have a net negative charge

Oppositely charged ions are

mutually attractive

COVALENT BONDS

\
* Electrons shared between atoms
* Results in polar or nonpolar molecules
* Common in organic molecules

Nonpolar

if electrons shared equally OR even distribution of charge

Polar

 if electrons not shared equally & *uneven* distribution of charge; forms weakly charges areas in molecule

___ molecule align themselves with other ____molecules

Polar; polar

What may change a molecule’s shape?

polarity

Chemical bond def:

a force of attraction that holds atoms together

Bonds may be ___, or ___, ____ in a chemical reaction

formed; broken; both

Most chemical reactions are reversible; T/F

True; most reactions are reversible

Chemical bonds represent

STORED ENERGY

______ is required to form bonds and is released when bonds are broken

Energy

What forms weak attraction within/betw. polar molecules?

hydrogen bonds

Hydrogen bonds cannot be broken by changes in temp./pH; T/F?

False; HB can be broken by changes in temp/pH

Hydrogen bonds are found in?

Proteins, Nucleic Acids, other large organic molecules & between water molecules

SYNTHESIS

\
Two or more substances combine to form a more complex substance

What is an example of synthesis?

Dehydration Synthesis

What is Dehydration Synthesis?

\
* Water released as bond forms
* E.g. Glucose molecules combine to form glycogen

DECOMPOSITION

One substance is broken down into two or more simpler substances

What is an example of decomposition?

Hydrolysis

Hydrolysis

• Water used to help break bonds

• E.g. Digestion of proteins into amino acids

• ex: h2o ⇆ H+ + OH-

Is decomposition the opposite of synthesis?

Yes; they are the opposite of each other

EXCHANGE

Combines synthesis & decomposition

* Bonds break & form

Example of an exchange reaction?

NaCl + O2- → Na2O + Cl-

Reversible Reactions

\
* The reaction can proceed in either direction
* The product may revert back to its original reactants or visa versa

What is an example of reversible reaction?

• ADP + ℗ + energy ⇋ ATP

• Common in living systems

Metabolism

all of the chemical reactions in our body

As chemical energy is exchanged, some is lost as heat, which is referred to as a

Source of body temperature

INORGANIC COMPOUNDS

\
* Don’t contain __both__ carbon and hydrogen
* Usually small, simple substances

Inorganic compounds common in cells:

\
* Water (H2O)
* Oxygen (O2) & Carbon dioxide (CO2)
* Salts (NaCl), some Acids, & some Bases

What is the most common inorganic compound in the human body?

water

Water can dissolve easily into itself; therefore it is a

solvent

Water characteristics?

\
* Absorbs & releases heat slowly
* Lubricates & cushions

What are salts regarding inorganic compounds?

Ionic compounds; dissociate in water

What is one source of important ions (electrolytes)?

salt

Salts contribute to the hardness or bones and teeth. T/F?

True; salts contribute to your bones and teeth

What is salt involved in?

\
Involved in blood clotting, muscle & nerve physiology

What are some examples of salts?

\
NaCl (sodium chloride) and CaCO3 (calcium carbonate)

What does the pH scale measure?

Measures \[H+\] in solution in log scale

What is acidic according to the pH scale?

What is basic/alkaline according to the pH scale?

> 7

Acids and Bases cannot dissociate in water. T/F

False; they can dissociate in water, but acid dissociates releasing hydrogen ions while base releases hydroxide ions

Acids release what in water?

hydrogen ions

What can strong acids do in water?

Strong acids completely dissociate in water (weak acids only partially)

Bases release what in water?

they release hydroxide ions

What does a base do when it interacts with a hydrogen ion?

it can form water

Buffers resist what in pH

changes

What is in a buffer?

weak acid and a weak base

What does a buffer do to make the solution relatively stable?

Pick-up H+ or OH- by having a weak acid/base

What are examples of buffers?

\
carbonic acid (H2CO3) + sodium bicarbonate (NaHCO3) 

Organic vs Inorganic molecules

Organic → BOTH CARBON AND HYDROGEN

Inorganic → HAS ONE OR THE OTHER; NOT BOTH OR NONE AT ALL

Organic molecules involve what bond?

covalent bonds

Covalent bonds are made and broken down by?

* Made by dehydration synthesis


* Broken down by hydrolysis

Organic molecules include?

\
* Carbohydrates
* Lipids
* Proteins
* Nucleic acids

Carbohydrates are built out of?

\
monosaccharide(s)

What are examples of carbohydrates?

sugars and starches

what is the major source of energy for making ATP?

carbohydrates

• common source = glucose

Monosaccharides

\
* Simple sugars
* Glucose, Fructose, Ribose, etc

Disaccharides

\
* 2 monosaccharides joined by dehydration synthesis
* Sucrose

Polysaccharides

\
* Long chain monosaccharides (complex carbs)
* Glycogen is a polymer of glucose

What do lipids contain?

Contain C, H, & O

What are lipids composed of?

Fatty Acids + Glycerol

Lipids are a source for what?

Source of maximum energy; long-term energy storage

Like dissolves with like T/F?

True; fats dissolve with fats and water dissolves with water