The Nature of Matter

What is matter? Matter: Anything that hass mass and volume Matter can be measured in these ways: Volume: amount of space that matter takes up Mass: a measure of matter’s inertia (more mass = greater inertia) -mass is always constant, no matter where the object is in the universe; weight is a measure of the force of gravity. Density: the mass of a given volume of a substance Length: You hopefully know what this is…

Physical properties of matter: Physical Property: Things that can be observed about a substance or object without changing the identity of the substance or object. Examples of Physical Properties: Color Odor Mass Volume How well it conducts electricity Malleablity (ability to be bent into shapes) Density ( d = m/v) State at room temeperature Heat or electricial conductivity Ductility (ability to be pulled in wire)

Characteristic property: Characteristic property: a property of a substance that can help identify a substance. Examples: Copper has a reddish color Water has a density of 1 g/ml Diamonds are much harder than other minerals.

Physical & Chemical Changes: Physical Change: a change in a substance that does not change the identity of a substance. (example: crumpling up a piece of paper.) Chemical change: a change in a substance that changes its identity (examples: setting a piece of paper on fire; iron rusting in salt water.)

Chemical Properties: Chemical properties describe matter’s ability to turn into other types of matter. Examples: Flammability: the ability to burn (be converted to energy) Reactivity: the ability to combine with other types of matter and become a new substance

Signs of chemcial change: Change in color Change in odor Creation of gas (fizzing, bubbling) Production of heat or other change in temperature Creation of light Creation of sound (e.g., explosion) The most important sign that a chemical change has occurred is that it cannot be easily reversed.

Elements vs. Compounds: Element: A substance which contains only identical atoms. Examples: hydrogen, helium, oxygen Molecule: A group of atoms that are connected (either by sharing or transferring electrons) Compound: A substance that contains two or more types of atoms that are chemically bonded togther. Examples: water, carbon dioxide

How to Read the Periodic Table:

Atoms vs. Isotopes Atom: is electrically balanced (number of electrons is equal to the number of protons) Isotope: the number of neutrons varies from the most-common variety listed in the periodic table. Example: Most atoms of carbon have 6 neutrons. However, some carbon atoms may have more or less than this number. Therefore, their mass may be more or less than the usual 12 AMU (atomic mass units)

Naming Isotopes: Isotopes of a given element are named (numbered) according to their mass number. Example: a carbon atom that has 6 protons and 8 neutrons has a mass of 14, so the name of that isotope is C-14.

Properties of isotopes: Generally, isotopes of an element have the same physical and chemical properties of other elements. However, some isotopes have unstable nucleii, and they decay rapidly (i.e, are radioactive.) For example C-14 is somewhat radioactive

Forces Within atoms (and throughout the universe): Gravity: exists because mass curves space-time Electromagnetic force: the force created by particles with positive or negative electric charges Strong nuclear force: the force that keeps particles in the atom from flying apart from one another Weak nuclear force: The force that that allows subatomic particles to turn into other types of particles (and is the cause of radioactive decay)