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Matter

Matter. Chapter 5 Lesson 1. What is matter made of?. Almost everything in the world around you is matter. All matter is made of the same basic building blocks…. Similar to legos .

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Matter

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  1. Matter Chapter 5 Lesson 1

  2. What is matter made of? • Almost everything in the world around you is matter. All matter is made of the same basic building blocks…. Similar to legos. • The models are different things but when you take them apart you would get the same building blocks and if you mix them up you cannot tell which model a block came from.

  3. Matter • All matter is made up of the same set of building blocks: the chemical elements. • Anelementis a material that cannot be broken down into anything simpler by chemical reactions.

  4. Aristotle • Aristotle( a Greek philosopher) believed that all matter is made of the elements earth, air, water, and fire. • Scientists know that this is not true and that the elements are not true elements. • Fire is not matter. Air and earth are made up of many different materials, not just one. • Water can be broken down into the simpler substances of hydrogen and oxygen. Hydrogen and oxygen cannot be broken down into simpler substances using chemical reactions. This tells us that hydrogen and oxygen are elements.

  5. Elements • MOST elements are solid, some are gases, and a few are liquid at room temperature. • SOME elements are more likely to combine with other elements to form new substances. These elements are Chemically Reactive. • Example: Magnesium is very reactive and is used in fireworks. Magnesium adds brightness to the fireworks.

  6. Smaller and Smaller • If you cut an element into half you will still have the same element. You will have two halves with the same properties of the original element. • If you keep cutting it into half you will eventually have the smallest piece of element possible. • John Dalton proposed in 1803 that elements are made of tiny particles. The believed that they tiny particles could not be cut into smaller pieces. • Today we know that Dalton’s particles exist and we call them Atoms. • Atoms are the smallest unit of an element that retains the properties of the element.

  7. Mercury • Mercury is an element that is a liquid at room temperature.

  8. Surprise!!!!!!!!! There is more information to know!! • Atoms are made of even smaller particles that are not elements. These particles are the same for every atom. • The nucleus is the center of the atom. It is made up of protons and neutrons. • The proton is a particle with one unit of positive (+) electric charge. The number of protons is the atomic number. This determines what element it is. • The neutron is a particle with no electric charge. It is neutral.

  9. Electrons • Atoms also contain electrons. These are similar particles with one unit of negative (-) charge. • Electrons move around in the space outside of the nucleus. • Usually the number of electrons and protons equal.

  10. Atomic Mass Unit (amu) • Protons and neutrons have about the same mass. This mass is called the atomic mass unit (amu). • If you add up the mass of all of the particles in the atom, you have the atom’s atomic mass. • In 1913 Niels Bohr pictured the atom’s electrons moving around the nucleus like planets moving around a star. We know today that the real picture is more COMPLEX. • The electrons around the nucleus act in many ways like a cloud of electric charge.

  11. Molecules • When you use legos to make something many parts act as one part. The same thing happens for atoms when they form molecules. • Molecules are particles with more than one atom joined together. • Most of the atoms in the world exist as a part of a molecule and not on their own. • When a molecule forms from elements, atoms link together through their electrons. • With about 112 elements, the number of different kinds of molecules that can be made is nearly infinite. • Molecules provide all of the variety around you.

  12. Chemical Formula • Scientists describe molecules by combining letters and numbers into a chemical formula. • The letters tell which type of element. • The numbers are known as subscripts, and they describe the amount of each element.

  13. How are elements grouped? • Each chemical element has a name and a symbol. • The symbols are one or two letters and the first letter is always capitalized. The second letter is never capitalized. • Some symbols look like the element’s English name. Others come from ancient names. • For example C=Carbon and Aa=gold whose Latin name is aurum • The element symbols are the same letters used in chemical formulas.

  14. Periodic Table • Dmitri Mendeleev made element index cards in 1869. • He ordered the cards from lightest to heaviest. • The led to the discovery that the properties of the elements repeat in cycles. • He made the cycles of the elements into rows in a table. • Each column contains elements with similar chemical properties. • Mendeleev’s table is called the periodic table.

  15. How do we examine elements? • Special electron microscopes use electrons instead of light particles to examine a sample. • They can show single atoms or the arrangement of atoms. • A scanning tunneling microscope shows single atoms also. It has a needle tip that moves over the surface. The needle is so sensitive that it moves up and down over each atom in the surface. • The up-and-down motions are turned into an image.

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