Lesson 1: What are atoms and elements?

 The smallest unit of an element that has the properties of that element.

 A substance made of only one kind of atom

 A table that shows the elements arranged by their atomic numbers

AA substance made of two or more different elements

AA group of two or more atoms that are joined

AA trait – such as color, shape, or hardness – that describes a substance by itself

AA combination of two or more different substances

 The smallest unit of matter is called an atom.  The simplest form of matter is called an element because it contains one type of atom.  Atoms are made of smaller particles such as protons, neutrons, and electrons. These particles are all alike.  The number of protons an atom has determines what element it is. Each type of atom has the properties of a certain element.  There are over 100 elements.

 Elements are the building blocks of matter. The 100 elements combine to form millions of substances.  Atoms of each element have a certain number of protons. An atom’s atomic number is the number of protons it has. They are listed on a periodic table.  All elements on the left side (except hydrogen) are metals.  On the far right side are nonmetals. The color blue shows gases.

 In nature, elements are rarely found in their pure form. They are mostly found in compounds, which are made of atoms from two or more elements.  A compound has a formula.  Pure substances include elements and compounds. In a pure substance, all particles are alike.  A molecule is the smallest unit of a compound that can exist in nature.  Sometimes, two atoms of the same element bond to form a molecule. This would include gases such as hydrogen, oxygen, and nitrogen.

 Physical properties are the traits that describe a substance.  A physical change is a change where a substance changes its state, but the substance remains the same.  Solubility is the ability to dissolve.  A mixture is when two or more substances combine and undergo a physical change when they mix, but they can be separated from the mixture.  A mixture where all the parts are mixed evenly is a solution.

 Bill Nye – Atoms k&feature=relatedhttp:// k&feature=related (Part 1 – 12:25) cU&feature=relatedhttp:// cU&feature=related (Part 2 – 9:36) - Making Molecules with Atoms (2:24) 6ZI