Download - Lexington JHS

Chapter 2- Matter
(has mass & takes up space)
Physical Properties
• matter that can be observed w/out
changing the identity.
ex. Color, odor, mass, volume, state,
freezing, melting, & boiling point, and…..
• Thermal conductivity –
•
•
•
ability to transfer
thermal energy
Malleability – can be
pounded into sheets
(aluminum foil)
Ductility – can be
drawn or pulled into a
wire.
Solubility – can
dissolve in another
substance
• Density is mass per unit volume
Formula D = m
V
Density of one substance is usually
different from another.
Good Egg vs Bad Egg
Density of Good Egg = 1.2 g/ml
Density of Bad Egg
Density of water
= .9 g/ml
= 1.0 g/ml
Result=
Bad Egg Floats
Changes in matter:
Physical vs Chemical
Physical Change – does not form a new
substance
(most can be undone)
Chemical Change – does form a new
substance
CANNOT BE UNDONE
Chemical changes often involve:
•
•
•
•
•
Color changes
Fizzing/foaming
Change in temp.
Sound/light
Odor
Chemical Properties
the ability to change into a new substance
w/ different properties.
i.e. Wood burns and becomes
smoke & ash
Chemical Properties
• Flammability – ability to burn
• Non-flammability – cannot burn
• Reactivity with - gas
acid
water
Elements-found on the periodic table
An element is a pure substance that cannot be
broken down into other substances.
(made of only one type of atom)
Ex. C, H, O, S, or Fe
Elements composed of atoms.
Atoms –basic particle from which all elements are
made
Compounds – a pure substance made of two or more
elements chemically combined in a set ratio. (different
properties than single elements)
H2O, CO2,C6H12O22
Chemical formula-shows ratio (shorthand)
Mixtures – made of two or more substances
not chemically combined.
Heterogeneous - you can see the different
parts
Homogeneous – evenly mixed that you
cannot see the different parts.
Example= solution
Mixture Separation
Magnet
Filtering
Distilling
Evaporation
What is Energy
• Energy is the ability to do work….
– And that work causes an object to move in
the direction of the force.
– It is expressed in units called Joules (J)
Forms of Energy
1. Chemical – energy
2.
required to bond
matter particles
together (toasting
marshmallows)
Thermal – is the
total kinetic energy
(energy of motion)
of the particles of
an object (from hot
to cold)
Thermal Imaging
Chemically bonded atoms
3. Electromagnetic (radiation) travels
through space as waves
ex. Radio, heat, & micro
4. Electrical- electrically charged
particles move from one place to
another
Endothermic vs Exothermic
Endothermic – energy is absorbed
i.e. Melted cheese sandwich – the cheese
takes in energy to melt.
The sun is also endothermic.
Exothermic – energy is released
i.e. Welding of any kind releases energy in
form of sparks and heat
Endo vs Exo Graphs
Endothermic Reaction
Activation energy-the amount of energy required to start a reaction