Atoms, Ions, and Molecules Chapter 2 Section 1
H O Living things consist of atoms of different elements. • ATOM – the smallest basic unit of matter • What is matter? • Something that has mass and takes up space • ELEMENT – a group of atoms of the same type • Examples: Hydrogen, Oxygen, Carbon, Nitrogen, etc.
Parts of the Atom • Nucleus (location – center of the atom) • Proton • Positive Charge (+) • Neutron • Neutral Charge (0) • Energy levels (location – surrounds nucleus) • Electrons • Negative Charge (-)
Atomic # & Atomic Mass • Atomic # • the # of protons (or electrons) • Atomic Mass • the # of protons and # of neutrons • # of Neutrons = Atomic Mass – Atomic #
Use the periodic table to complete the table shown below: Au 79 118 79 He 2 2 2
Electron Energy Levels • First Energy Level • Maximum of 2 electrons (e-) • Second Energy Level • Maximum of 8 e- • Third Energy level and beyond • Stable with 8 e- in outer shell
Oxygen atom (O) outermost energy level: 6 electrons (-) Nucleus:8 protons (+)8 neutrons inner energy level: 2 electrons (-)
Bonding • Not all atoms have full outer shells • They are not “happy” or “stable” • They form bonds with other “unhappy” atoms to complete their outer shells • Compound – a substance made of atoms of different elements • Examples: CO2, H20, NaCl, CH4
REVIEW • How are elements different from compounds? • How many electrons are needed to fill the outer energy level of oxygen? Compounds are made of different elements 2
Ionic Bonding • An ion is an atom that has gained or lost one or more electrons. • positive ions (lose electrons) • negative ions (gain electrons) Ionic bonds form between oppositely charged ions. Example: NaCl
Covalent Bond • Covalent bonds form when atoms share one or more pairs of electrons - produce strong bonds - examples: CO2, CH4, H2O Molecule – two or more atoms held together by covalent bonds - examples: N2, H2, O2, CO2, H2O
It’s show time…. • Work as a team to develop a skit demonstrating each type of bonding!
REVIEW • What happens to electrons in outer energy levels when two atoms form a covalent bond? • What distinguishes one element from another? • Describe the formation of an ionic compound. • What is the difference between an ionic bond and a covalent bond? • How does a molecule differ form an atom?
REVIEW • What happens to electrons in outer energy levels when two atoms form a covalent bond? • Pairs of outer energy level electrons are shared • What distinguishes one element from another? • The number of protons in the nucleus • Describe the formation of an ionic compound. • One atom loses an electron, the other one gains an electron. The oppositely charged ions formed are attracted to each other. • What is the difference between an ionic bond and a covalent bond? • Electron pairs are shared in covalent bonds. Ionic bonds form when electrons are transferred and the oppositely charged ions attract. • How does a molecule differ form an atom? • A molecule is made up of two or more atoms held together by covalent bonds.
Exit ticket: Answer one of the questions below using complete sentences: • What part of an atom do you think would be the most fun and why? • Relationships—which type of bonding would you like to be involved in and why?
Investigate Van der Waal’s forces and the gecko! http://www.youtube.com/watch?v=OoYeIsSkafI http://www.youtube.com/watch?v=gzm7yD-JuyM http://www.youtube.com/watch?v=HTbrsx1zARs