Transcript Ch 8 Matter
Chapter 8 Earth Chemistry 8.1 – Matter ► Every object in the universe is made of some kind of substance. ► Matter is that substance. Matter is anything that takes up space and has mass. ► The amount of matter determines how much mass an object has. 8.1 - Matter ► All matter has 2 types of distinguishing properties. ► Physical properties can be observed without changing the composition of the substance ► Examples: Density, color,hardness, freezing and boiling points 8.1 - Matter ► Chemical properties show how a substance interacts with other substances to produce different kinds of matter ► For example: iron interacts with oxygen to form rust. Helium usually doesn’t interact with other substances 8.1 – Atoms and Elements ► Matter is made up of Elements. ► An element is a substance that has all of the same physical and chemical properties. ► Every element has a symbol that is either one capital letter or a capital letter followed by a lower case letter ► Ex. Hydrogen = H and Iron = Fe 8.1 – Atoms and Elements ► Over 90 elements can be found on earth ► About 15 more have been made in a lab ► Only 8 elements make up 98% of earth’s crust ► Silicon and Oxygen make up 75% of the crust 8.1 – Atoms and Elements ► Elements are made of atoms ► An atom is the smallest unit of an element that has all the properties of that element ► The word “atom” comes from greek meaning “indivisible” ► Atoms of one element are very different from atoms of another element 8.1 – Atoms and Elements ► To get an idea of the size of a single atom, look at the edge of a piece of paper. More than a million atoms lined up side by side would equal that thickness 8.1 – Atomic Structure ► Atoms are made of even smaller particles called subatomic particles ► There are three kinds : protons, neutrons, and electrons ► Protons are positively charged ► Electrons are negatively charged ► Neutrons do not have a charge 8.1 – Atomic Structure ► Protons and neutrons are packed close to one another in the middle of the atom in what is called the nucleus ► Because protons are positive and neutrons don’t have a charge the nucleus has a positive charge ► The nucleus takes up as much space in an atom as a gumball in a football stadium 8.1 – Atomic Structure ► Around the nucleus is mostly empty space. It is called the electron cloud. ► Electrons are in the electron cloud. ► Because electrons are negative, they are attracted to the positive nucleus. ► They are constantly moving at extremely high speeds ► Protons and Neutrons are 1800 times bigger than electrons