Transcript PPT #1

Chemistry:
THE STUDY OF MATTER

So what is matter?
Matter
 Must
 It
have mass
is different from weight…..Why?
 Must
occupy space (have volume)

Therefore: all matter has a measurable density

Density of a Substance
=
Mass
Volume
States of Matter

Matter can exist in three basic states:


Solid (s), Liquid (l), Gas (g)
How are these states different from each other?
Can Matter be Destroyed?

Example:

When 400 grams of wood are burned only about 30 grams of ash
remain.

Why does the matter weigh less?

What happened to the missing matter?
Law of Conservation of Matter

Matter cannot be
created or destroyed
Matter isn’t being lost
but changing in form!

During reactions
atoms are all still
there, they just get
rearranged

Chemical equations are “balanced” with
coefficients to obey this law.
Basic Types of Matter
Elements
•
Made of atoms of one specific type
•
Have specific properties.
•
Cannot be broken down further by a chemical
reaction
Examples of Elements
Elements and Their Symbols

Element symbols are
composed of either one or
two letters

If two letters, the second
letter is written lower case.

Ex:


Write Cu for copper not CU
Why is this so important?
Just Read:

Usually it is pretty easy to match an element
to its symbol (Ex: Neon = Ne)

Sometimes the symbol is derived from a Latin
name for the element.
 Ex:
Au = gold (comes from Latin word aurum)
Some Tricky Elements






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
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Na = sodium
K = potassium
Fe = iron
Cu = copper
Sb = antimony
Sn = tin
Pb = lead
Hg = mercury
W = tungstun
Au = gold
Ag = silver
Phases of Elements at STP

Gases:
 H, He, Ne, Ar, Kr, Xe, Rn,
N, O, F, Cl

Liquids:
 Hg, Br

Solids:

All other elements are solids

Let’s make a note of these on our
Periodic Tables!
Diatomic Elements

Composed of two identical
bonded atoms

Note: Most elements are
monoatomic in pure form.
Who are they?
 Remember BrINClHOF

Let’s make a note of these on
our Periodic Tables!
Compounds

Two or more different elements bonded
together
Ex: C6H12O6, NO2, CO2, NaCl

Note: Most elements in nature do not exist in
their pure state, but in compounds.

Why? They are more “stable” that way.
•
Compounds have formulas
that show the proportion of
elements to each other.
•
Ex: Water is always H2O
•
This is called the “Law of
Definite Proportions”

Compounds have different
properties than the elements
they are composed of.
Ex:
Sodium (Na)
Chlorine (Cl)
Toxic metal
Toxic gas
Sodium Chloride (NaCl)
White edible crystal
Focus Question
 What
makes atoms of one element
different from another?

http://www.pbslearningmedia.org/asset/lsps07_int_theatom/
Atomic Basics

Atoms consist of three basic parts.
Protons
 Neutrons
 Electrons


Fill in Chart:
Particle
Proton
Neutron
Electron
Charge
Mass
Location
Symbol

Atomic Number:
Tells us the number of
protons in nucleus
 It is unique for each
element
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Atomic Charge

Atoms are neutral particles

Number of electrons (-) = number of
protons(+)

How many electrons does an atom of carbon
have?
Nuclear Charge

Nuclear Charge:
 the
charge on the nucleus of the atom.
 (+) positive charge = to number of protons
What is the Nuclear Charge?
What is the Atomic Number?
What is this Element?
Ionic Charge

Ions: atoms with a charge
Protons don’t equal electrons!!
 Atom has gained or lost electrons

 Gain
electrons: become (-) ion
 Lose electrons: become (+) ion
P=9
E = 10
What is the element? What is it’s ionic charge?
Ionic Charge Practice
Try a few for practice…
Finding the Atom’s
Mass

Mass Number:


Sum of the number of protons + neutrons
Each has a mass of 1 amu. (atomic mass unit)
Ex:
P = 23
N = 21
What is the Atomic Mass Number?
What is this element?
Isotopes

Isotopes: atoms of the same element with
different atomic mass.
Same # protons
 Different # neutrons

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Ex: Carbon-12, Carbon-13, Carbon-14
 How
many protons?
 How many neutrons?
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Average Atomic Mass:

Atomic mass you see on periodic table
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Represents the average mass of all the
isotopes of an element in a typical sample.

Based upon abundance of each isotope and
their mass
Calculating Average Atomic Mass

Mass of each isotope x abundance
(change % abundance to decimal)
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Add together answers

Ex: Chlorine
Crash Course Kids: What is Matter?
 https://www.youtube.com/watch?v=ELchw
UIlWa8&safe=active

Crash Course: Atomic Basics
 https://www.youtube.com/watch?v=FSyAe
hMdpyI
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