Science: Lesson 2 What Makes Up Matter? All matter is made up of what? Each element is made of only one kind of atom. An atoms is the smallest particle of an element that has the same properties of the element.

More About Atoms Too small to be seen. Atoms have: Nucleus (has neutrons and protons) Neutrons = no electrical charge Protons = positive charge # of protons = element’s atomic number (identifies element) Example = only carbon atoms have 6 protons, carbon’s atomic # = 6 Electrons = negative charge, surround atom’s nucleus **Scientists have suggested that protons and neutrons are composed of smaller particles called QUARKS (Six identified so far) A particular arrangement of 3 of these quarks produces a proton. Another arrangement of 3 produces a neutron

More About Atoms The Electron Cloud Model of the Atom: the area around the nucleus where electrons are most likely to be found. The electron cloud is 100,000 times larger in diameter than the diameter of the nucleus of an atom. Each electron in the cloud is significantly smaller in mass than a single proton or single neutron.

Molecules Also too small to be seen. Atoms can combine to make molecules Smallest part of a substance made from more than one atom that still has the properties of that substance Also too small to be seen.

An Element’s Information Symbols of one or two letters Atomic Number on top = # of protons in nucleus **Way in which we identify different elements. Atomic Mass on bottom= # of protons and the number of neutrons.

Isotopes Atoms of the same element can have different mass numbers. For example, carbon atoms can have a mass number of 12, and also 14. For an elements mass number to change, the number of neutrons must change. Atoms of the same element that have different numbers of neutrons are called isotopes.

Dmitri Mendeleev Invented the Periodic Table of Elements in 1869 Mendeleev noticed patterns in elements which led him to create the first Periodic Table. He identified about 65 elements. Arranged elements in rows according to increasing mass. Atoms of elements that are in the same group (columns) on the periodic table have similar physical and chemical properties.

Periodic Table of Elements Organizes about 100 elements by columns and rows Rows = periods, tells how many shells for electrons they have. Period one = one shell, period seven = seven shells In a periodic table, a set of properties repeats from row to row or period to period. In general, goes from reactive (explosive) on the left to non-reactive on the right Columns = Groups, each element in a group has similar properties. Example = far right group 18 are gases at room temperature, “noble gases”

The Periodic Table of Elements is organized into three groups: Metals cobalt Non-metals carbon - diamonds Metalloids silicon

Metals Solid copper Good conductors of heat and electricity Made into wires = ductile Bent & hammered into sheets = malleable iron aluminum gold

Metals Pure metals = made up of only one kind of atom (gold, silver, iron, nickel,) Alloy = Not pure elements, made up of more than one kind of atom. Steel is a mixture of iron and carbon Brass is a mixture of copper and zinc Bronze is a mixture of copper and tin

Non-Metals chlorine Usually brittle Poor conductors of heat and electricity Can’t be made into wire Can’t be hammered into sheets Neon Nitrogen Oxygen

Metalloids Have some properties of both metals and non-metals Arsenic Bismuth Boron

Hydrogen Hydrogen belongs to a family of its own. Is a reactive gas. Was involved in the explosion of the Hindenberg. Is promising as an alternative fuel source for automobiles

Alkali Metals 1st column on the periodic table (Group 1) not including hydrogen. Very reactive metals, always combined with something else in nature (like in salt). Soft enough to cut with a butter knife

Alkaline Earth Metals Second column on the periodic table. (Group 2) Reactive metals that are always combined with nonmetals in nature. Several of these elements are important mineral nutrients (such as Mg and Ca

Transition Metals Elements in groups 3-12 Less reactive harder metals Includes metals used in jewelry and construction. Metals used “as metal.”

Boron Family Elements in group 13 Aluminum metal was once rare and expensive, not a “disposable metal.”

Carbon Family Elements in group 14 Contains elements important to life and computers. Carbon is the basis for an entire branch of chemistry. Silicon and Germanium are important semiconductors.

Nitrogen Family Elements in group 15 Nitrogen makes up over ¾ of the atmosphere. Nitrogen and phosphorus are both important in living things. Most of the world’s nitrogen is not available to living things. The red stuff on the tip of matches is phosphorus.

Oxygen Family or Chalcogens Elements in group 16 Oxygen is necessary for respiration. Many things that stink, contain sulfur (rotten eggs, garlic, skunks,etc.)

Halogens Elements in group 17 Very reactive, volatile, diatomic, nonmetals Always found combined with other element in nature . Used as disinfectants and to strengthen teeth.

The Noble Gases

The Noble Gases Elements in group 18 VERY unreactive, monatomic gases Used in lighted “neon” signs Used in blimps to fix the Hindenberg problem.