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 C 6 H 12 O 6 – 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/cm 3

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 /multimedia/chapter3/lesson1 /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 /multimedia/chapter6/lesson8 /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 /multimedia/chapter6/lesson1 /multimedia/chapter6/lesson1 Lessons 1-7