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 Benchmark SC.8.P.8.5  Recognize that there are a finite number of elements and that their atoms combine in a multitude of ways to produce compounds.

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Presentation on theme: " Benchmark SC.8.P.8.5  Recognize that there are a finite number of elements and that their atoms combine in a multitude of ways to produce compounds."— Presentation transcript:

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2  Benchmark SC.8.P.8.5  Recognize that there are a finite number of elements and that their atoms combine in a multitude of ways to produce compounds that make up all of the living and non-living things that we encounter Combination of elements to form compounds

3 Compounds two or more elementschemically combined A compound is a substance which is made up of two or more elements that have been chemically combined together. Elements chemically combined? What do you mean?

4 Put the two together = sodium chloride!! Table Salt, a perfectly safe, edible compound Sodium- is a soft silvery white metal that reacts violently with water Compounds Chlorine-is a poisonous, greenish yellow gas. + Sodium chloride (table salt) Table salt is made out Sodium and Chlorine. Cannot be separated by physical means! It is different to Sodium and different to Chlorine!

5 A compound… two or more elementschemically combined.  Is a substance which is made up of two or more elements that have been chemically combined.  Can be chemical means  Can be broken down into a simpler type of matter (elements) by chemical means (but not by physical means).  Has properties different elements.  Has properties that are different from its component elements. Ex: In a water molecule Hydrogen and Oxygen are gases but when they combine together they form a liquid. same ratio  Always contains the same ratio of its component atoms. Ex: In a water molecule there are 2 Hydrogen atoms per every Oxygen atom (H2O). And in a peroxide molecule there are 2 Hydrogen atoms per every 2 Oxygen atoms. Let’s check!

6 What is a compound? Cu Is this a compound? It only contains one type of element. Is this a compound? H H H H O O O It is not chemically combined. Why not? two or more elementschemically combined A compound is a substance which is made up of two or more elements that have been chemically combined together. H It only contains one type of element. O H H O H H O H H Yes! Is this a compound?

7 Examples of compounds ACIDS taste sour and turn blue litmus paper red. BASES feels slippery and turns blue litmus paper darker blue.

8  Compounds (2+ Elements)  2 or more elements that have combined chemically. (bonded)  Can have different properties than the elements that make them up.  Example – water  Water is different than the elements hydrogen and oxygen. Types of Substances Created from the Periodic Table

9  Mixtures ( Heterogeneous )  Combination of 2 or more substances that have NOT combined chemically.  Substances can be easily separated and still have their own identities.  Example: A supreme pizza. Every piece has a different ratio of toppings. I can pick them of and each piece is its own entity. Types of Substances Created from the Periodic Table

10  Solutions (homogeneous)  Combination of 2 or more substances that have NOT been combined chemically  The solution has the same properties throughout.  Example: Bronze is a solution. In order to be created a specific ratio of copper and tin must be mixed together. If you look at a piece of bronze, you cannot tell that there are two different elements present. Types of Substances Created from the Periodic Table

11 ACIDS  Produce H + (as H 3 O + ) ions in water  Tastes sour.  REACTS with metals  React with bases to form salts and water BASES BASES  Produce OH - ions in water  Taste bitter, chalky  Feel soapy, slippery  React with acids to form salts and water

12 { Atoms! The Legos of the Universe

13 The Atom Atom: the smallest unit of matter, a nucleus surrounded by an electron cloud.  “atom” is from the Greek word “atomos” which means “not able to be divided.”

14 Inside the atom All atoms are made of the same 3 subatomic (smaller than an atom) particles.

15 Inside the atom…

16 Inside the nucleus of an atom

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18 Key Questions  If there are both protons and neutrons in the nucleus, why does the nucleus have a positive charge? Protons are positive, and neutrons are neutral, so they don’t give any charge!

19 Outside the nucleus…

20 The Atom Electron Nucleus Neutron Electron Cloud Proton + - 0

21 How Do You Weigh an Atom?  What units do you use to measure the mass of an atom?  Atomic Mass Units (AMU) Atomic Mass Units (AMU)  1 AMU = Mass of one proton  1 AMU = Mass of one neutron

22 Sizes of Subatomic Particles  How big are protons, electrons, and neutrons compared to each other? Big Tiny

23 Summary of Key Concepts ParticleChargeMass (AMU)Location Proton+1Nucleus Electron-1/1830 ≈ 0Electron Cloud NeutronѲ1Nucleus

24 Summary of Key Concepts  Protons (+) = Electrons (-)  #Neutrons = Atomic Mass – Atomic Number  Atomic Mass = # Protons + # Neutrons

25 Formative Checkpoint (Fill in this table) Does it Have CELLS? Does it have ATOMS? Living Things Non-Living Things

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27 Elements  The elements, alone or in combinations, make up our bodies, our world, our sun, and in fact, the entire universe.

28 Key to the Periodic Table  Elements are organized on the table according to their atomic number, usually found near the top of the square.  The atomic number refers to how many protons an atom of that element has.  For instance, hydrogen has 1 proton, so it’s atomic number is 1.  The atomic number is unique to that element. No two elements have the same atomic number.

29 What’s in a square?  Different periodic tables can include various bits of information, but usually:  atomic number  symbol  atomic mass  number of valence electrons  state of matter at room temperature.

30 Atomic Number  This refers to how many protons an atom of that element has.  No two elements have the same number of protons. Bohr Model of Hydrogen Atom Wave Model

31 Atomic Mass  Atomic Mass refers to the “mass” of the atom.  It is derived at by adding the number of protons with the number of neutrons. H This is a helium atom. Its atomic mass is 4 (protons plus neutrons). What is its atomic number?

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33 ADD a Proton from left to right

34 Families Periods Families Periods  Columns of elements are called groups or families.  Elements in each family have similar but not identical properties.  For example, lithium (Li), sodium (Na), potassium (K), and other members of family IA are all soft, white, shiny metals.  All elements in a family have the same number of valence electrons.  Each horizontal row of elements is called a period.  The elements in a period are not alike in properties.  In fact, the properties change greatly across even given row.  The first element in a period is always an extremely active solid. The last element in a period, is always an inactive gas.

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46 Hydrogen  The hydrogen square sits atop Family AI, but it is not a member of that family. Hydrogen is in a class of its own.  It’s a gas at room temperature.  It has one proton and one electron in its one and only energy level.  Hydrogen only needs 2 electrons to fill up its valence shell.

47 Alkali Metals  The alkali family is found in the first column of the periodic table.  Atoms of the alkali metals have a single electron in their outermost level, in other words, 1 valence electron.  They are shiny, have the consistency of clay, and are easily cut with a knife.

48 Alkali Metals  They are the most reactive metals.  They react violently with water.  Alkali metals are never found as free elements in nature. They are always bonded with another element.

49 Matter  All matter is composed of atoms and groups of atoms bonded together, called molecules.  Substances that are made from one type of atom only are called pure substances.  Substances that are made from more than one type of atom bonded together are called compounds.  Compounds that are combined physically, but not chemically, are called mixtures.

50 Elements, Compounds, Mixtures  Sodium is an element.  Chlorine is an element.  When sodium and chlorine bond they make the compound sodium chloride, commonly known as table salt.  Compounds have different properties than the elements that make them up.  Table salt has different properties than sodium, an explosive metal, and chlorine, a poisonous gas.

51 Elements, Compounds, Mixtures  Hydrogen is an element.  Oxygen is an element.  When hydrogen and oxygen bond they make the compound water.  When salt and water are combined, a mixture is created. Compounds in mixtures retain their individual properties. The ocean is a mixture.

52 Elements, compounds, and mixtures  Mixtures can be separated by physical means.  Compounds can only be separated by chemical means.  Elements are pure substances. When the subatomic particles of an element are separated from its atom, it no longer retains the properties of that element.


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