Combination of elements to form compounds

1. Combination of elements to form compounds • 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

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

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

4. Let’s check! A compound… • Is a substance which is made up of two or more elements that have been chemically combined. • Can bebroken down into a simpler type of matter (elements) by chemical means (but not by physical means). • 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. • Always contains the same ratioof 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.

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

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

7. Types of Substances Created from the Periodic Table • 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.

8. Types of Substances Created from the Periodic Table • 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.

9. 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

10. ACIDS Produce H+ (as H3O+) ions in water Tastes sour. REACTS with metals React with bases to form salts and water BASES • Produce OH- ions in water • Taste bitter, chalky • Feel soapy, slippery • React with acids to form salts and water

11. Atoms! The Legos of the Universe

12. 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.” The Atom

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

14. Inside the atom…

15. Inside the nucleus of an atom

16. Inside the nucleus of an atom

17. 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! Key Questions

18. Outside the nucleus…

19. - Electron Nucleus + 0 Neutron The Atom Proton Electron Cloud

20. 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 How Do You Weigh an Atom?

21. How big are protons, electrons, and neutrons compared to each other? Big Tiny + 0 - Sizes of Subatomic Particles

22. Summary of Key Concepts

23. Protons (+) = Electrons (-) • #Neutrons = Atomic Mass – Atomic Number • Atomic Mass = # Protons + # Neutrons Summary of Key Concepts

24. Formative Checkpoint(Fill in this table)

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

27. 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.

28. 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.

29. 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

30. 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. This is a helium atom. Its atomic mass is 4 (protons plus neutrons). What is its atomic number? H

32. ADD a Proton from left to right

33. 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. Families Periods

34. Families(Groups)

45. 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.

46. 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.

47. 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.

48. 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. Matter

49. 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.

50. 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.