Atoms, Elements, Periodic Table, Compounds, Mixtures

1. Atoms, Elements, Periodic Table, Compounds, Mixtures Section 1: Atoms

2. ATOMS:

3. 1)An atom is the smallest part of an element that still has the properties of that element. • (the smallest part of “stuff” that is still “stuff”)

4. 2)Parts of an Atom: a) nucleus: made of protons and neutrons b) electron cloud: composed of electrons and empty space Electron cloud nucleus

5. 3)Particles that make up an atom: a) protons: positively charged b) Electrons: negatively charged c) Neutrons: NO charge (neutral) Two hydrogen atoms are walking along the street. One suddenly goes: - Oh shoot, I´ve lost an ' electron! Other one says: -Are you sure? – Yes, he replies.- -I'm positive.

6. 4) Atoms differ from one another because of the number of protons in the nucleus. -this is called the atomic number (all atoms with the SAME atomic number belong to the same element)

7. 5) Isotopes: atoms of the same element, with a different number of neutrons.

8. Tell me . . . 1) What are the three particles that make up an atom? 2) What is the center of an atom called? 3) What makes one type of atom different from another?

9. 6) The number of protons in an atom added to the number of neutrons gives what is called the mass number. If you take the mass numbers of all the different isotopes that exist, and average them together, you get what is called the Atomic mass. Atomic number Atomic mass

10. Elements

11. An element is • a pure substance • that cannot be broken down into simpler substances by physical or chemical means. • All atoms of the same atomic number are of the same element.

12. 2) A pure substance is one that has only one type of particle. Elements and Compounds are both pure substances.

13. 3) Elements can be identified by their characteristic properties: • remember those? • properties that don’t change no matter the size of the substance • things like boiling point, • melting point, • density and • reactivity

14. Explain how an element is different from an atom. Are characteristic properties physical or chemical or both?

15. Periodic Table

16. 1) Elements are organized on the Periodic Table of Elements by atomic number.

17. 2) Periodic Table -columns are called groups or families (because they behave in a similar fashion)

18. 2) Periodic Table – cont: Rows are called periods: Elements show a gradual change in properties across a period.

19. 3) Elements are grouped into three categories based on similar properties: metals, non-metals, Metalloids

20. 4) metals: shiny, good conductors, malleable, and ductile Ex: iron, aluminum Iron filings

21. 5) Nonmetals: dull, poor conductors, brittle Ex: carbon/graphite Sulfur Noble gases Neon sulfur Argon is used in light bulbs

22. 6) metalloids: properties of both called semiconductors Ex: silicon This has nothing to do with metalloids – it just amused me.

23. If you know the category, you know the properties, and for an unknown element, if you know the properties you can figure out the category.

24. Name the three categories of elements found on the Periodic Table. How are periods and Rows on the Periodic Table different?

25. Section 2: compounds

26. 1) A compound is a pure substance composed of two or more elements that are chemically combined. Ex: water, salt Compounds are considered pure, because each particle of NaCl is identical to every other particle of NaCl

27. 2) Compounds are created through a chemical change and can be broken down through a chemical change

28. What is the difference between an element and compound? What can compounds be broken down into?

29. 3) Elements in a compound are combined in a specific ratio. Carbon dioxide (CO2) will always have 2 atoms of oxygen for every one atoms of carbon All the particles are the same so it is a pure substance

30. Molecule 4) A molecule is a neutral group of atoms held together by covalent bonds (nonmetals bond with non metals sharing electrons) Example-water H20

31. 5) Chemical Formulas • A chemical formula is a shorthand notation for a compound or a diatomic element using chemical symbols and numbers. • A chemical formula indicates the chemical makeup by showing how many of each kind of atom is present in a molecule. Ex: H20 is the chemical formula for water • H2O Element oxygen Element hydrogen Subscript number 2

32. What does the numbers in the formula H2O2 tell you about this formula? What does H mean? What does O mean?

33. Section 3: Mixtures

34. 1) A mixture is a combination of two or more substances that are not chemically combined. Video link

35. Properties 2) Substances in a mixture retain their identities. 3) Mixtures can be physically separated • Ex: picking off the pepperoni on your pizza

36. Properties 4) Some mixtures are harder to separate than others because you don’t always see all of the materials in that mixture. • Example: salt water

37. Properties 5) Mixtures do not have definite ratios • Ex: air is a mixture • 78% Nitrogen • 21% Oxygen • 1% other gases

38. 6)Types of Mixtures • Two types of mixture: • Homogeneous mixture-mixed the same throughout (milk) • Heterogeneous mixture-mixed differently throughout (Italian dressing)

39. 7)Techniques for Separating Mixtures • Mixtures are physically separated here are some common techniques • Distillation • Magnet • Centrifuge

40. 8)The common types of mixtures: a) solutions b) suspensions c) colloids

41. What is the difference between a compound and mixture? Name three techniques you can use to separate mixtures.