Unit 1 (Chapter 2.1 - 2.5)

Matter

Anything that has mass and occupies space.

Element + give an example

A substance that CANNOT be broken down into simpler substances by chemical means. Elements are the building blocks of matter and consist of atoms. EX: Hydrogen

Compound + give an example

A substance with 2 (or more) different elements combined in a fixed ratio.

Ex: NaCl

Emergent Properties

A compound with different physical and chemical properties then the elements that make it up. (Ex: Na = Metal, Cl = Poisonous Gas, NaCl = Table Salt)

What are the 3 Elements that make up 96% of living matter?

1. Carbon

2. Hydrogen

3. Oxygen

List the 3 Subatomic particles that make up an Atom

1. Protons (+)

2. Neutron (x)

3. Electrons (-)

Explain the Basic general information of the atomic structure

structure, mass #, atomic #, isotopes

Structure = Protons + Neutrons are in the Atomic Nucleus (Held by Nuclear Force), Electrons surround the Nucleus forming the “Electron Cloud” (Held by Electromagnetic force from positive charge in Nucleus)

Mass # = tells you the total of Protons + Neutrons

Isotopes = An atom of the SAME element (SAME # of Protons) but with a different amount of neutrons

What are the types of Bonds and Methods

1. Covalent: The sharing of a pair of valence electrons by 2 atoms

• Non Polar - electrons are shared EQUALLY

• Polar - electrons are shared UNEQUALLY (pulling)

2. Ionic: A chemical bond between oppositely charged ions (electrons are transferred between one another)

• Anion: Negatively charged (GAINS e)

• Cation: Positively charged (LOSES e)

Explain the Electron Shells, Orbitals, and Valence Electrons

Valence shell = the OUTERMOST electron shell

• ex: the hotel floor

Valence orbitals = the orbitals WITHIN that shell that contain or can contain the valence electrons (the limit of electrons on each shell)

• ex: the rooms on the hotel floor available

Valence Electrons = the electrons on the outermost shell

How does Electronegativity determine polar or nonpolar covalent bonds?

The MORE electronegativity, the HARDER an element will pull on a shared electron. If both atoms have a similar electronegativity then nonpolar.

What is the difference between a hydrogen bond and van der Waals interactions?

hydrogen bond = WEAK, chemical bond formed when the hydrogen atom (which is slightly positive) of a polar covalent bond in one molecule is attracted to a slightly negative atom of a polar covalent bond in another molecule

van der Waals = WEAK, caused between molecules or parts of molecules that result from temporary local partial charges.

What are the 4 MAIN properties of water?

1. Cohesion (The ability to stick together)

• Adhesion = water sticking to OTHER subst.

2. Moderation of Temp (High Specific Heat)

• water can ABSORB and RELEASE large amts of heat w/o change in its own temperature

1. Expansion upon freezing (ice = less dense then water)

2. Versatility as a Solvent (Universal Solvent)

Explain the molarity of an aqueous solution.

Molarity tells you how many moles of solute are dissolved in 1 liter of solution

• higher molarity → more solute in x amt of solution

• lower molarity → less solute in x amt of solution

Define pH

A scale that helps determine how much Hydrogen is in an aqueous solution → -log [H+]

> 7 = Less H+, higher pH (BASE)

< 7 = More H+, lower pH (ACID)

Acid vs Base

Acid (<7) = more H+ then OH-

Base (>7) = more OH- then H+

What are Buffers & their importance?

Buffer = A substance that keeps pH stable / shock absorber

• prevents BIG changes in H+/OH- in acids & bases