Transcript Chapter 7: Atoms and Molecules - Help, Science!

What is matter?
• Chemistry is the study of matter and how
matter interacts with each other
• Matter is made up of small particles called
atoms
– An atom is the smallest part of matter/an element
that can be recognized as that element
• Back to this later…
Chemical and Physical Properties
of Matter
• Chemical properties are properties that
describe how matter interacts with each other
• Physical properties describes the material
which composes the matter
Physical Properties
• Density- how much matter is packed into a
given volume
• Malleability- the ability to be pound into a
sheet
• Ductility- the ability to be drawn into a wire
• Conductivity- the ability to conduct an
electrical charge
• Shape, size, color
Physical Changes
• A Physical change does not change the
identity of the matter
– Examples include:
• Change of state of matter (melting, freezing,
vaporization)
• Cutting a block of wood
• Adding dye to water
Chemical Properties
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Reactivity
Combustibility
pH
Electromotive force
Chemical Changes
• A chemical change forms a completely new
product
– The identity of the matter completely changes
– Examples
• Rusting
• Burning
• Salt formation from the neutralization of and acid and
or base
Pure Substances
• Pure substance
– cannot be separated into 2 or more substances by
physical or mechanical means
– is homogeneous, i.e., has uniform composition
throughout the whole sample
– its properties are constant throughout the whole
sample
– its properties do not depend on how it is prepared
or purified
– has constant chemical composition
Mixtures
• A mixture:
– can be separated into 2 or more substances by
physical or mechanical means
– displays the properties of the pure substances
making it up
– its composition can be varied by changing the
proportion of pure substances making it up
– heterogeneous substances, ones with nonuniform composition throughout the sample, are
always mixtures
Elements
• Classifying Elements
– Chemical symbols- are abbreviations for the
names of the elements
• The first letter of a chemical symbol is always a capital
letter
• The second (and third) letter (s) are always lower case
• A capital letter always indicates a new element
• CO= Carbon and Oxygen – Carbon monoxide, a gas
• Co= Cobalt, a metal
Compounds
• When atoms join together with other atoms
to form units they are called molecules
• The process of combining different types of
atoms is called a chemical change or chemical
reaction
• Compounds- are the products of chemical
changes
– A combination of 2 or more different atoms types
of elements
Common Compounds
• H2O- water
• NaCl- sodium chloride- table salt
The Atom
Atoms
• Atoms are made of three particles
– Nucleus- condensed center of an atom
• 1. Protons- positively charged particles inside the
nucleus of an atom
• 2. Neutrons- neutral/no charge particles inside the
nucleus of an atom
– Shells- space surrounding the nucleus of an atom
• 3. Electron- negatively charged particles travelling
around the nucleus of an atom
Atomic Number
• The atomic number is the number that
represents the element- it is the number of
protons in a given atom/element
What is energy?
• Energy is the ability to do work and these
atoms are working all the time.
Energy Forms
• Energy comes in many different forms
– Potential energy- energy due to position
– Kinetic energy energy in motion
– Electrical energy forces that move electrically
charged particles
– Chemical energy energy responsible for making
and breaking chemical bonds
– Nuclear energy cause by the removal or addition
of particles in the nucleus of an atom
Conservation of Matter and Energy
• Now it is important to note that matter and
energy cannot be created nor destroyed only
transferred from one form to another
– The Law of Conservation of Energy
• The 1st law of thermodynamics
Law of Entropy
• Now all of this matter and it energy is
constantly changing forms and is constantly
moving towards a state of disorder or
randomness- entropy
2nd Law of Thermodynamics
• This law states that all natural processes tend
toward the highest entropy and minimal
useable energy
– Entropy or disorder is always increasing
5 States of Matter
• Solid- particles are tightly packed, usually in a regular
pattern.
– particles vibrate (jiggle) but generally do not move
from place to place.
• Liquid- particles are close together with no regular
arrangement.
– Particles vibrate, move about, and slide past each
other.
• Gas- particles are well separated with no regular
arrangement.
– Particles vibrate and move freely at high speeds.
States of Matter
• Plasma- this is an ionized gas. It is gas that
has so hot that it acts as a liquid
– The particles are packaged similarly to a liquid
• Bose Einstein?
– It is a super fluid with some odd characteristics
– It is super cold, it exists at absolute 0