Matter and its Changes

1. Matter and its Changes

2. Atoms • Matter is made up of atoms • Matter is anything that takes up space and has mass • Atoms are the “building blocks” of life

3. Forms of matter that contain only one type of atom are called elements • Atoms combine to form many different types of matter

4. Structure of an Atom Electron (electron cloud) Proton Mass Number = Protons + Neutrons Atomic Number = Number of protons Neutron

6. Isotopes • When the number of protons in an atom changes it becomes a different element • Atom is electrically neutral when there are more neutrons than protons • Atoms of the same element that have a different number of neutrons are called isotopes • Ex. C12 = 6p +6n C14 = 6p + 8n

8. Ions • Electrically charged atoms are called Ions • The number of protons is not equal to the number of electrons • Ions are attracted to each other when they have opposite charges • Ex. Na+ + Cl- = NaCl = salt • Ex. Na+ + F- = Sodium Fluoride for toothpaste

9. Combinations of Atoms

10. Atoms combine by sharing their outermost electrons in their electron clouds • When two atoms are combined a molecule is formed

11. Bonds • Ionic Bond – Positive and Negative ions combine and electrons are transferred • Ex. NaCl • Covalent Bond – Electrons are shared • Ex. H2O

13. Combinations of Atoms

14. How Atoms Combine • When at least two atoms are combined a molecule is formed • There are two ways in which atoms combine to form molecules and compounds

15. Ionic Bonding • Positive and Negative ions combine and electrons are transferred • Example: Na+ and Cl- = NaCl

16. Covalent Bonding • In covalent bonding electrons are shared • Example: 2H + O = H2O

17. Compound A type of matter that has properties different from the properties of each of the elements in it • Example: Na (metal) + Cl (gas) = NaCl (solid salt) • Example: 2H (gas) + O (gas) = H2O (liquid water)

18. Mixture • Many different substances that when mixed together, each substance retains its own properties • Examples: sand, air and salad

19. Solution • When one substance of a mixture is dissolved in another substance it is a solution • Examples: tea w/ sugar, salt water

20. Chemical/Physical Properties • Chemical properties describe how one substance changes when it reacts with another • Examples: iron and oxygen = rust • Physical Properties can be observed or measured without changing the substance • Examples: color, shape, size, density and texture

21. Density

22. What is density? • The measure of the mass of an object divided by its volume.

23. 4. Liquid to a solid: freezing point 5. Solid to a liquid: boiling point 6. Only substance that occurs naturally as a solid, liquid, and gas: Water

24. Matter can change by: • Increasing or decreasing the temperature Ex: freezing water turns it to a solid (ice) 2. Increasing or decreasing pressure Ex: Pressure to ice cube changes it to liquid

25. Energy from Atoms • What is nuclear energy? • Alternate energy source produced from atomic reactions 2. How fission produces nuclear energy: - Splitting the nucleus of atoms in heavy elements

26. 3. Most commonly used fuel in nuclear power plants: - Uranium 235 Where is it found? - Sandstones in the Rocky Mountains

27. 4. Major source of nuclear waste: - Radioactive material Most common method of storing nuclear waste: • Power plants Can remain active for 10,000 years

28. Two advantages to storing nuclear waste at Yucca Mountain: • Remote area (deserted) • Water table is far below storage facility

29. Two disadvantages to storing nuclear waste at Yucca Mountain: • Earthquakes could destroy storage facility • Large amount of nuclear waste in one area