Classifying Matter Take out a pencil and the following vocabulary cards: Atom 3. Element 9. Nucleus 10. Proton 11. Neutron 12. Electron 13. Electron cloud 14. Atomic number 15. Isotope 15. Ion 18. Anatomy of an Atom 19. Possible changes in Atoms 21. Chemical bond 4. Molecule 2. Substance 5. Compound 6. Mixture 7. Heterogeneous mixture 8. Homogeneous mixture

1. Atom Building blocks of all matter The study of atoms and their smaller particles is called the atomic theory Many different types of atoms (elements) Mostly empty space In natural processes, atoms are not destroyed, they are recycled In a neutral atom, the number of protons is the same as the number of electrons

1. Atom

Made up of atoms (~100 trillion/cell) Atoms vs. Cells Atoms Cells Have a nucleus Building blocks of everything Have a nucleus Building blocks of every living thing Made up of atoms (~100 trillion/cell)

Nuclear Fusion The nucleus of one atom combines with the nucleus of another atom Hydrogen to Helium The 1 proton in the hydrogen atom combines with the 1 proton in another hydrogen atom New atom has two protons

How Atoms Formed The Big Bang Hydrogen and helium form stars Stars became more compact and hotter in the core (enough energy for nuclear fusion) At least 25 million degrees F for helium At least 180 million degrees F for carbon, oxygen, etc. Stars die and explode releasing elements and creating higher level new elements

Synthetic Atoms Created artificially (man-made) Some may exist in the universe, but not on Earth Most don’t last long (some exist for only a split second) Few useful synthetic atoms Plutonium: creates energy, used in nuclear weapons, highly toxic

18. Anatomy of an Atom

9. Nucleus Region at the center of an atom that contains most of the mass of the atom Composed of protons and the neutrons Always has a positive charge (positive proton + neutral neutron)

10. Proton Positively charged particle in the nucleus of an atom Number of protons determines the identity of every element # of protons = atomic number

11. Neutron Uncharged particle in the nucleus of an atom The number of neutrons on an atom is the atomic mass – the atomic number Usually the heaviest part of an atom

10. Electron Negatively charged particle that occupies the space in an atom outside the nucleus Electrons furthest from the nucleus have the most energy Electrons can travel in any direction around the nucleus

10. Electron Cloud The region surrounding an atom’s nucleus where one or more electrons are most likely to be found Contains mostly empty space Electrons can be located closer to the nucleus or further out

18. Anatomy of an Atom

3. Element Substances made of only one kind of atom Identity of an element depends on the total number of protons it has (its atomic number)

14. Atomic Number The number of protons in the nucleus of an atom of an element Every element in the periodic table has a different atomic number You can identify an element if you know either its atomic number or the number(s) of protons its atoms have

15. Isotope One of two or more atoms of an element having the same number of protons, but a different number of neutrons In nature, most elements are found as mixtures of isotopes Isotopes of an atom have the same chemical behavior

16. Ion An atom that has a charge because it has gained or lost electrons Cation – ion with a + charge - remove electron(s) Anion – ion with a - charge – add electrons

19. Possible Changes in Atoms Neutral Atom Change # of Particles Type of Atom Element Symbol 6 protons 6 neutrons 6 electrons +1 neutron 7 neutrons Isotope C +1 electron 7 electrons Ion C- +1 proton 7 protons New element - nitrogen N

21. Chemical Bond A force that holds two or more atoms together Negatively charged electrons are attracted to the positively charged nucleus Electrons closer to the nucleus are more strongly attracted to the nucleus and vice-versa The outermost electrons can be attracted to another atom’s nucleus This attraction creates a chemical bond between the atoms

4. Molecule Two or more atoms that are held together by chemical bonds and act as a unit Ex. Table sugar – C12H22O11 One grain of sugar contains trillions of these molecules Give substances their identity

2. Substance Matter with a composition that is always the same Bonded at atomic level Always contains the same kinds of atoms in the same combination All elements are substances

3. Element Substances made of only one kind of atom Identity of an element depends on the total number of protons it has (its atomic number)

5. Compound Substance made of two or more elements that are chemically joined in a specific combination Ex. H2O – water always has two hydrogen atoms and one oxygen atom Changing the composition of a compound changes it into a new compound with new properties (ex. H2O2 – hydrogen peroxide) Each has a chemical formula

6. Mixture Matter that can vary in composition Not chemically bonded Can be physically separated Ex. Salt water – you can change the amounts of salt or water and it’s still salt water Can be any state of matter

7. Heterogeneous mixture Mixture in which the substances are not evenly mixed Different substances are visible by unaided eye or under microscope Can be separated by physical separation, magnets (if part of it is magnetic), etc. Hetero - different

8. Homogeneous mixture A mixture in which two or more substances are evenly mixed, but not bonded together Also known as a solution Can be separated by boiling or evaporation Can’t tell the differences between substances under a microscope (where one begins and the other ends) Ex. Brass, lemonade and air

Combining Atoms Concept Map Element Homogeneous mixture Compound Heterogeneous mixture Mixture Substance Chemical Physical Solution