properties of matter. matter anything that has mass and takes up space matter can take many forms...
TRANSCRIPT
Properties of Matter
Matter
Anything that has mass and takes up space
Matter can take many forms and is not always visible to the eye
Matter can change form
Everything in the universe is made of matter
Energy, thoughts, feelings, ideas, sounds, light, heat, and emotions are not matter
Matter is made of atoms Matter can neither be
created nor destroyed; it just changes form - Law of Conservation of Matter
Atoms
Tiny particles that make up matter
They are so small that 1 million atoms lined up side by side are equal to the thickness of a human hair
“atom” comes from a Greek word that means “cannot be divided”
Atoms are the smallest unit of matter that has the identity of the matter
Atoms are in turn made of protons, electrons, and neutrons
Protons, electrons, and neutrons are called subatomic particles
Proton
Positively charged particle Located in the nucleus of an
atom
Electron Negatively charged particle Located outside the nucleus of
an atom
Neutron
Neutral particle, no charge Located in the nucleus of an
atom
Types of Matter - Elements
Most kinds of matter are made of combinations of a basic group of building blocks called elements
Element - matter made up of only one type of atom
There are about 116 different elements
Compounds
Compounds are matter made up of different kinds of elements, chemically bonded together
Compounds
When elements combine to make compounds, the new substance has properties that are different from the properties of the elements that made it.
Compounds
Na (sodium) is a very reactive metal and Cl (chlorine) is a poisonous gas
NaCl is table salt and tastes delicious on potato chips!
Chemical Formula Uses symbols and numbers to
represent the elements found in a substance and the number of each of those elements
Every element has a 1 to 3 letter symbol to represent the element, use the Periodic Table to match the symbol with the element
Chemical Formula - examples NaOH – Has 1 atom of Na (sodium), 1
atom of O (oxygen) and 1 atom of H (hydrogen) This is the formula for sodium hydroxide
C6H12O6 – Has 6 atoms of C (carbon), 12 atoms of H (hydrogen) and 6 atoms of O (oxygen) This is the formula for glucose.
Identifying Elements and Compounds
Elements and compounds can be identified by their properties
Scientists must do different tests to identify elements and compounds correctly
Identifying Elements and Compounds
It can take several tests and it helps to compare unknowns with known examples
Sometimes scientists also need to study the atomic and subatomic structures of matter to make a correct identification
Identifying Elements and Compounds
There is no simple test to tell whether a substance is an element or a compound
Properties
Characteristics or features of a substance
Substance – a general term for a compound or element (a fancy word for “stuff”)
Physical Properties
Characteristics of a substance that can be measured or observed without changing the identity of the substance
Physical Properties: examples
Size Shape Texture Color Density State of Matter (solid, liquid,
gas)
Physical Properties: Density Compares the mass of
something to how much space it takes up
Density = mass/volume To calculate density, divide the
mass of an object by its volume
Units for density: g/mL or g/cm3
Physical Properties: Density Density is a property that can
be used to identify a substance If you know the density of an
unknown substance, you can compare it to a list of densities of known substances and find a match
Link to a site with short lessons about density
http://www.middleschoolchemistry.com/multimedia/chapter3/lesson1
Physical properties: Solubility
Solubility – ability of one substance to dissolve in another (usually a solid in a liquid)
Soluble substances form solutions
Physical properties: Miscibility Miscibility – ability of one liquid
to mix with or dissolve in another liquid
Immiscible liquids don’t mix Less dense liquid floats on the
denser liquid
Chemical Properties of Matter
A characteristic of a substance that allows it to change into a new substance
Characteristics that relate to the atomic or elemental composition of substances
Chemical Properties of Matter – Examples Examples of chemical
properties: flammability (ability to burn),
ability to react with oxygen, reactivity (how easily one thing
reacts with another), or toxicity (how poisonous
something is)
Link to a site with short lessons about pH
http://www.middleschoolchemistry.com/multimedia/chapter6/lesson8
Lessons 8-10
pH pH is a scale used by scientists
to measure the acidity or basicity of a substance
pH 7 is neutral pH 1 up to pH 7 is acidic pH greater than 7 up to pH 14
is basic
pH pH is a chemical property pH is used to predict chemical
reactions or to select compounds for specific chemical reactions
Acids and bases are reactive compounds
Physical and Chemical Changes
Physical Changes
Any change in size, shape, form, or state of matter
The makeup of the matter stays the same, only the physical properties change
Examples of Physical Changes
Physical weathering Cutting or breaking something Change in state of matter
Changes in State of Matter Solid to liquid – melting Liquid to gas – evaporating
or boiling Gas to liquid – condensation Liquid to solid – freezing or
solidifying
Chemical Changes
Any change where one or more of the original materials changes into a new material
They can take place quickly or slowly (rusting)
Signs of chemical changes Heat or light can be released
Signs of chemical changes A new substance can be formed –
a gas is released, a solid or liquid forms
More signs of chemical changes Sometimes heat (energy) is
absorbed Sometimes a color change
happens
Link to a site with short lessons about chemical reactions
http://www.middleschoolchemistry.com/multimedia/chapter6/lesson1
Lessons 1-7