Matter and Energy Notes

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Transcript Matter and Energy Notes

Matter
What is Matter?
Matter is anything that takes up space and
has mass
 Some matter you can see (your lab table)
and some you cannot (the air around you)

Matter varies in characteristics because of the
atoms that make it up
 Atoms are “building blocks” of matter


Element- substance that cannot be broken
down into simpler substances by chemical
or physical means (iron, copper,
hydrogen)
Periodic Table- Organizes the
Elements
Periodic Table

112 known elements


92 naturally occur and others are produced in
the lab
The periodic table is organized by periods
(rows) and groups (columns)
Organizing the Squares
V C
E O
R L
T U
I
M
G
R
O
U
P
C N
A S
L
PERIODS
Horizontal Rows
Organizing the Squares
The Periods
The table has 7 periods (rows)
1st period has 2 elements
2nd period has 8 elements
3rd period has 8 elements
4h period has 18 elements
etc
Organizing the Squares
The Groups
Groups are numbers from 1 to 18 from left
to right
 Some groups are given family names
 Notice the different colors on the table
below
 Group 1=Alkali metals
 Group 2= Alkali Earth Metals
 etc

Organizing the Squares
Metals, non-metals, and
semimetals



Metals – shiny, good conductors of heat and
electricity, solid (Hg liquid), etc
Non-metals – do not have properties above
Semimetals – or metalloids – have some
properties of metals
Elements
Each element is represented by a symbol
 Each element also has an atomic number
which represents the number and protons
and a mass number which represents the
mass (and number) of protons + neutrons
 http://www.ptable.com/
 The number of electrons in an atom will
equal the number of protons, (unless the
atom is an ion)

The most abundant elements in
Earth’s crust
Element
Oxygen
Silicon
Aluminum
Iron
Calcium
Sodium
Potassium
Magnesium
All others
Approximate
% by weight
46.6
27.7
8.1
5.0
3.6
2.8
2.6
2.1
1.5
Atoms and Matter
Atoms- Nucleus + Electrons
 Nucleus- contains protons and neutrons

Protons and Neutrons- Nucleus

Protons have a (+) charge

The number of protons in an atom of an element is equal
to the atomic number of the element
Neutrons are neutral (they have no charge)
 Mass of individual protons is approximately 1
and mass of individual neutrons is
approximately 1
 Mass number = mass of protons + neutrons
(and) number of protons + neutrons

ElectronsSurround the nucleus
The smallest of the fundamental particles
of an atom
 The part of the atom involved in chemical
bonding
 Mass- 1/1836 the mass of a proton or
electron
 Electrons move so rapidly around the
nucleus that they create a sphere
shaped zone

Electrons
The number of electrons in an atom is
always the same as the number of protonsunless the atom is an ion
 Ions- have extra electrons (giving the ions
a negative charge) or have less electrons
(giving the ions a positive charge)
 Examples- Ca+2, Na+, Cl

Which of these has extra electrons? Which
have electrons taken away?
Calculating number of Protons,
Neutrons, and Electrons

Carbon (C) has an atomic number of 6
and an atomic mass of 12.011
How many protons? How many neutrons?
 How many electrons?


Gold (AU) has an atomic number of 79
and an atomic mass of 196.97.
How many protons? How many neutrons?
 How many electrons?

Isotopes
Isotopes are atoms that have the same
number of protons, but have different
numbers neutrons. The mass number of
these atoms would be different
 Carbon has 15 different isotopes

Carbon 12 makes up 99% of the carbon on
Earth and has 6 protons and 6 neutrons
 Carbon 13 has 6 protons and 7 neutrons
 Carbon 14 has ? Protons and ? neutrons

Chemical Bonding and States of
Matter
11.
12.
13.
14.
15.
Energy – the ability to do work
Potential energy – stored energy due to
position or location
Orbital – the 3D space in which an
electron has a good probability of being
found
Valence electrons – the outer most shell
of electrons
Covalent bonds – atoms that combine by
sharing valance electrons
Ionic bond – a type of bonding in
which one atom strips away an
electron from another atom
17. Ion – a charged atom
18. Chemical reaction – the making
and breaking of chemical bonds
19. Reactants – the starting materials
in a chemical reaction
20. Products – the result of a
chemical reaction
16.
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Atomic Theory of Matter
Dalton's Atomic Theory (John Dalton, English
chemist, 1766-1844)
 1) All matter is made of atoms. Atoms are
indivisible and indestructible.
 2) All atoms of a given element are identical in
mass and properties
 3) Compounds are formed by a combination of
two or more different kinds of atoms.
 4) A chemical reaction is a rearrangement of
atoms.
Modern Atomic Theory

Dalton’s theory remains valid, but modern
theory is more descriptive
1) atoms can be destroyed by nuclear
reactions, but not chemical reactions
2) there are different forms of atoms of
elements called isotopes which have the
same properties
How compounds form
Individual atoms combine in a process
called chemical bonding.
 The type of bond is determined by how
many electrons are found in the outermost
energy level (orbital).

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Chemical Bonding

Valence Electrons- the electrons on the outer
orbital of an atom which may participate in
chemical bonding.
 All other electrons are known as inner-shell
electrons
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Chemical Bonding

Label the valence electrons on your periodic table
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Octet Rule

Octet Rule- The tendency for atoms of elements
to gain, lose, or share electrons so that their
outer orbital (valence orbital) is full with eight
electrons.
 There are a few exceptions: Hydrogen,
Helium, Lithium, and Beryllium ions have
outer shells that need only 2 electrons to be
full.
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Chemical Bonding
Atoms gain, share, or lose electrons to get 8
electrons in their outer shells to become
STABLE.
 When they do this, they form bonds
 There are 3 main types of bonds
 Ionic Bonds
 Covalent Bonds
 Metallic Bonds

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Remember…
Protons are Positively charged (p+)
 Electrons are Negatively charged (e-)
 An atom has equal number of positive and
negative charges.
 Same number of protons and electrons.
 Atoms are electrically neutral, but they can gain
or lose electrons to become ions.

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Ionic Bonds
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Ions

Ion- an atom or group of atoms that has
an electric charge because it has lost or
gained electrons
 Cation- an ion that has a positive
charge.
More protons than electrons.
 Anion- an ion that has a negative
charge.
More electrons than protons.
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Ionic Compound



Any chemical compound that is composed of
oppositely charged ions.
Elements in groups 1 and 2 and in groups 16 and
17 will almost always form ionic compounds.
The force of attraction between the ions’ positive
and negative charges create an ionic bond.
 Ionic bonding occurs between metals and
nonmetals.
 Metals usually lose electrons and nonmetals
gain electrons.
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Ions
It is easy to tell which ion an element will form
based on their group number
Group 1= +1
 Group 2 = +2
 Group 13 = +3
 Group 14 = doesn’t usually form ions
 Group 15 = -3
 Group 16 = -2
 Group 17 = -1
 Group 18 = doesn’t usually form ions

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Ionic Bond
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Chemical Formulas for Ionic
Bonds

If the charges of the ions cancel out, then
you can just write the element symbols
together:
 Na+1
+ Cl-1 = NaCl
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Chemical Formulas for Ionic
Bonds

If they are not equal, then the
superscript of one ion becomes the
subscript of the other ion:
 Ca +2
=
+ Cl-1
CaCl2
 Notice
that 1 is not written
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Covalent Bonding
Occurs between nonmetal and
nonmetal
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Covalent Bonds –

A covalent bond is formed when atoms share
electrons

Atom is unstable when the outside energy level is not
filled
Example - Individual hydrogen
atoms have 1 electron but want
2. In this state they are unstable.
By sharing electrons they are
stable.
Molecule: A group of atoms
held together by covalent bonds
(they have no overall charge)
Hydrogen
atoms
H2
Covalent Bond



Neither atom in a covalent bond has enough
attraction to completely take an electron from the
other atom (to become an ion); so the electrons
are shared.
Because the atoms share electrons, covalent
bonds are much stronger than ionic bonds.
Atoms in covalent bonds can share 1, 2, or 3
pairs of electrons.
 The more electrons are shared, the stronger
the bond between the atoms.
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Review Chemical Bonds
Covalent VS Ionic Bonds
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Metallic Bonds are…
 How
metal atoms are held
together in a solid.
 Metals hold on to their valence
electrons very weakly.
 Think of them as positive ions
(cations) floating in a sea of
electrons
A Sea of Electrons
Sea of Electrons
 Electrons
are free to move through
the solid.
 Therefore Metals conduct electricity.
+
+ + +
+ + + +
+ + + +
Metals are Malleable
 Can
be hammered into shape
(bendable)
 Also ductile - drawn into wires.
 Both malleability and ductility
are possible because of the
mobility of the valence
electrons
Malleable
Force
+
+ + +
+ + + +
+ + + +
Malleable

Mobile electrons allow atoms to slide by,
sort of like ball bearings in oil.
Force
+ + + +
+ + + +
+ + + +
Ionic solids are brittle
Force
+
+
-
+
+
+
+
-
+
+
Ionic solids are brittle

Strong Repulsion breaks a crystal apart,
due to similar ions being next to each
other.
Force
- + - +
+ - + - + - +
Chemical Reaction
A
process in
which one or
more
substances are
converted into
new substances
with different
physical and
chemical
properties
Before reaction
After reaction
Chemical Reaction Definition
– Substances present
before a chemical reaction
 Product – Substances present
after a chemical reaction
 Therefore, a chemical reaction
can be states as reactants
changing into products
 Reactant
Reasons for Reactions
 An
atom with an incomplete set of
valence electrons will bond.
 Atoms
try to obtain a complete set of
valence electrons and thus become
more stable by reacting with other
substances
States of Matter
Solid, Liquid, Gas, Plasma
 The movement (or lack of movement) of
atoms results in different states of matter

States of Matter

SolidsAtoms are in a fixed position, they vibrate but
do not change position
 They have a definite size and shape
Liquids Molecules are close together and move freely
 Takes the shape of its container
Gases Molecules are freely moving and independent
 Completely fills its container



Write down the properties of each state of matter!!!!
A solid holds shape and has a fixed volume, a liquid……
Plasma
Most of the matter in the universe is in the
plasma state
 Matter in this state is composed of ions
and electrons



Most electrons are found outside the electron
cloud
Stars are composed of matter found in the
plasma state
Phase Changes in Matter
Factors determine state of matter
1)
2)
Attraction between atoms
Rate of movement of atoms
Temperature and pressure can affect
these factors
Increase temperature (SI Unit?)= Increase in movement
Increase pressure = Decrease in space between atoms

Click here to run simulation
Physical Properties of Matter
Can observe these with our senses!
 Density
 Color
 Smell
 Hardness
 Melting Point
 Boiling Point
 Ability to conduct electricity
 Magnetism
physical change


alters form or appearance of
material, but does not
change material into brand
new substance
examples
 chopping wood
 bending wire
 molding clay
 phase changes
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Chemical Properties
Are only observable during a chemical
reaction
 paper burns
 iron rusts
 gold does not rust
 wood rots
 nitrogen does not burn
 silver does not react with water
 sodium reacts with water
chemical properties


observed only when substance is
changed and interacts with
another substance
examples


flammability: able to burn
rusting: combining with oxygen
to form rust
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