Transcript Properties of Matter-Forensic Science

Background for Glass Analysis
Quiz Monday 10/03
•
Matter is anything that has mass and
takes up space.
–Mass: the number of particles in
something, how much there is of an
object
–Space: scientific word for “space” is
volume, which describes the size of a
substance.
–Both of these variables can be
observed and measured
We
can measure mass using a triple
beam balance or digital scale.
Mass is measured in grams (SI Unit)
We
can measure volume using a
ruler or a graduated cylinder
Volume can be measure in two ways:
• Volume of a regular solid (cube):
L xW x H
• unit: cm3
• Volume of a irregular
solid (rock):
 Density
is defined as mass per unit of
volume
 The formula for density is…
density = mass
volume
 If
the density of the object is
greater than that of the fluid,
the object will sink.
 If
the density of the object is
equal to that of the fluid, the
object will neither sink or
float (suspended)
 If
the density of the object is
less than that of the fluid, the
object will float.
SOL ID
LIQUID
GAS
 Plasma
least common form on Earth - but most common in the universe
• radiation from the sun, light from a
fluorescent light, stars
Amorphous
solid
• Greek amorphos, from a- (without) +
morphē (form)
• Non-crystalline solid
• Can change shape with heating
• Heating at a range of temperatures- not a
set temperature like a crystalline solid
• Behaves more like liquids with high
viscosities
• EX: honey, syrup, & gels
Matter is Classified into 2 groups
1
. Physical Property: any property
of an object that can be observed
without changing it’s composition
(without changing what the object or
substance is made up of)
EX: weight, volume, color, boiling or melting point,
viscosity, brittleness, buoyancy, phase changes
 For
the forensic scientist, the need to find
and measure those properties that will
associate one glass fragment with
another--also minimizing or eliminating
other sources.
 To
compare glass fragments, a forensic
scientist evaluates two important
physical properties: density and
refractive index.
Chemical
Property: a characteristic
of a substance that indicates whether
it can undergo a certain chemical
change
• Flammable
• Reaction to light
• Reaction to sound
Chemical
Change: a change of one
substance to another, an “unexpected”
change
 Burning, fizzing, or popping (fireworks
exploding) are helpful indicators that a
new substance is produced.
 Routine
drug tests for
cocaine or heroine- fast
test before sending to lab
for detailed analysis
 Uses
a chemical reagent
called Marquis reagent.
 Chemical
reaction occurs
turning the unknown
sample various colors
detecting the type of
drug
Can test for ecstasy, meth,
aspirin, codeine, LSD, morphine
 Ancient
Greek philosophers suggested
that earth, air, water, and fire as matters
fundamental building blocks
 Atom
=
basic unit of matter
Elements: Substance
in which all atoms
in a sample are alike
Compounds: substance
made of two or
more atoms (two or more elements)
Water:
Salt:
Hydrogen
and
Oxygen
Sodium
and
Chlorine
Molecules
 Silica(SiO2)
is a common
fundamental constituent
of glass.
Element or compound?
Transfer of a
substance
into glass
FUN FACT:
In nature, vitrification of quartz occurs when
lightning strikes sand, forming hollow,
branching root like structures called fulgurites.