Science Grade 5 Chapter 5: Comparing Kinds of Matter Lesson2: Elements

Transcription

1 Element: is a material that cannot be broken down into anything simpler by chemical reactions. o There are 118 elements o Most elements are solids, some are gasses and few are liquid at room temperature o Elements are either metal or nonmetals or metalloids o Magnesium is a very chemically reactive elements and is used in firework Metals: are elements that share common properties such as shiny luster, conductivity and flexibility. Example: sodium, copper and gold Nonmetals: are elements that are poor conductors, dull, and brittle. Example: chlorine and oxygen. Metalloids: are elements that have properties between metals and non-metals. Example: silicon Atom: is the smallest unit of an element that retains the properties of that element. Nucleus: is the center of an atom. It is made of protons and neutrons. Proton: is a particle with one unit of positive electric charge Atomic number: the number of protons in an atom and determine which element it is. Neutron: is a particle with no electric charge. It is a neutral Electrons: smaller particles with one unit of negative electric charge Atomic mass unit: the mas of protons and the mass of neutrons (mass of protons = mass of neutrons) Molecules: are particles with more than one atom joined together Chemical formula: describe molecules by combing letters and numbers o Letters tell which type of atoms are in the molecule o Subscripts: are the numbers which indicate the number of each atom Element symbol: are one or two letters where the first letters always capital and the second letters are never capital. Periodic table: is table orders elements from lightest to the heaviest where each column contains elements with similar chemical properties 1

2 Most common elements in space are hydrogen and helium The elements hydrogen, oxygen, silicon, aluminum nitrogen, iron and calcium are the most common elements on earth. The core of Earth is solid iron. Most of oxygen and hydrogen come from water About 60% of animal body weight is water Plants and animals are mainly made of carbon, hydrogen and oxygen Heavier elements tend to collect in the crust while lighter elements reside in the oceans and atmosphere Scientist can observe atoms with special electron microscope and the scanning tunneling microscope Note: please look to the Periodic Table of Elements in the text book page

3 is the smallest unit of an element that has the properties of that element. o atom o physical property o chemical property Which of the following is an example of an element? o Rust o Hydrogen o Carbon Dioxide o Water Most elements are o gases o metals The smallest unit of an element is o atom o metal o element The properties of elements are determined by the structure of their o matter o particles o gases o atoms Elements in the periodic table are arranged by o Atomic Number o Atomic Weight o Number of Neutrons o Chemical properties An element that is a good conductor of heat and electricity is called a o metal o nonmetal o metalloid o plastic 3

4 Elements are organized in a table called the table. o periodic o element o compound Which of the following is a gas we breathe? o Gold o Iron o Oxygen o Silver An element is a substance made up of several kinds of atoms. o True o False What is an element? o the basic substances from which all other substances are made o an atom with no charge o chemicals that have reactions o metals that have no properties The basic building blocks of matter. o Atom o Elements A substance made up of only one kind of atom is an element. o True o False Which element is most likely to be dull? o Carbon o Aluminum o Mercury o Sodium 4

5 Elements in their natural form are o Gases only. o Solids and liquids. o Liquids only. o Gases and liquids. o Solids, liquids or gases. How is the periodic table organized? o The table is arranged according to the number of protons. o The elements in each column have similar chemical properties. o Both A and B o Neither A nor B What property do metals have in common? o They have the same color. o They are poor conductors of heat. o They are good conductors of electricity. o They are all solids at room temperature Chlorine is an example of o Metalloids o Metal are elements that are poor conductors, dull, and brittle o Periodic table o Nonmetals o Metals o Metalloids Which element is most likely to conduct heat and electricity? o Nitrogen o Aluminum o Helium o Oxygen The smallest particle of an element that has the properties of that element is an o Atom o Elements 5

6 There are approximately elements. o 90 o 100 o 118 o 218 Scientist can observe atoms with o Thermometer o the scanning tunneling microscope o graduated cylinder o periodic table is a very chemically reactive elements and is used in firework o Sodium o Aluminum o Mercury o Magnesium is the center of an atom. It is made of protons and neutrons. o Atomic number o Nucleus are elements that share common properties such as shiny luster, conductivity and flexibility. o Nonmetals o Metals o Metalloids o Periodic table are elements that have properties between metals and non-metals. o Nonmetals o Periodic table o Metals o Metalloids 6

7 Most common elements in space are o Hydrogen and Helium o Hydrogen and Oxygen o Carbon and Hydrogen o Nitrogen and Carbon are particles with more than one atom joined together o periodic o element o atom Plants and animals are mainly made of o helium, hydrogen and oxygen o carbon, magnesium and oxygen o carbon, hydrogen and oxygen o carbon, hydrogen and nitrogen Scientist can observe atoms with o Thermometer o special electron microscope o graduated cylinder o periodic table and are examples of nonmetals elements o carbon, magnesium o chlorine and oxygen o magnesium and copper o silicon and chlorine About of animal body weight is water o 50% o 60% o 70% o 90% 7

8 A copper coin would best be classified as a o Nonmetal o Molecule o Metal o Metalloid Which has a negative charge? o Nucleus o Neutron The drawing below shows a water molecule. The arrow is pointing to a (n) o Atom o Nucleus Scientist can use a scanning tunneling microscope to o Study the shape of a water molecule. o Form new elements. o Change the density of an object o Measure an objects weight What are the building blocks of matter? o atom o metal o element The chemical formula for carbon dioxide is CO 2. Is carbon dioxide an element? explain