1. CH2 Sec1 Matter and Substances

2. Everything is made up of matter. Matter is anything that has mass and takes up space.

3. Matter is made up of Atoms Atoms are the smallest unit of matter Atoms have positively charged center (core) surrounded my negatively charged region

4. Atomic Structure Made up of three kinds of particles:  Protons – (+) positively charged  Electrons – (-) negatively charged  Neutrons – No charge

5. Protons and neutrons make up the core (center or nucleus) Electrons move around the nucleus in an electron cloud

6. Elements Are made up of atoms that have the same number of protons – Elements found within the same column have similar properties Isotopes are atoms of an element that have different numbers of neutrons

7. Periodic Table

8. Determining # of electrons, protons, and neutrons in atom Atomic # = # protons Protons = electrons Atomic mass = p + n

9. Determining # of electrons, protons, and neutrons in atom Atomic # = # protons (27) Protons = electrons (27) Atomic mass = p + n – 32 neutrons Now you try a few….

10. Chemical Bonds Electron cloud of an atom may have levels Innermost level can hold only 2 electrons Levels farther from the nucleus can usually hold 8 electrons Electrons in the outermost level (shell) are called valence electrons, this is where atoms bind

11. Chemical Bonds Opposites attract Atoms come together and form a chemical bond Making the atoms more stable they want an even number of electrons in each level, forming a neutral charge A compound are created when atoms from two or more different elements bond Ions are atoms that have a + or - charge as a result of gaining or losing electrons

12. Covalent BondIonic Bond Electron pairs are shared Molecules are produced Bond is the attraction for shared electrons Example: Water Molecule H 2 0 Electrons are transferred Ions are produced Bond is the attractions between ions of the opposite charge Example: Table Salt Na + Cl - Covalent Bond and Ionic Bond

13. Table salt is an Ionic Compound because the positive Na (sodium) ion loses an electron to negative Cl (chloride) ion. Positive to Negative. + ----

14. Polarity Molecules charges on opposite ends are polar – One end is positive the other opposite end is negative.

15. Solubility Polar molecules that attract opposite charges Water dissolves polar molecules such as salt and sugar – Nature’s Solvent Not able to break the bonds of non-polar substances like wax, oil, or grease – Important characteristic of our cell membranes

16. Hydrogen Bonds Play important role Holds DNA strands together Type of weak covalent bond