Summer Biology Chapters 2 & 3 Atoms ● Atoms: fundamental building blocks of matter ● Nucleus ○ Positively charged protons ○ Uncharged neutrons (except for hydrogen) ● Electrons: move around the nucleus ○ Negatively charged ● Atoms come together to make molecules, which then come together to make macromolecules, which then come together to form organelles, which then form cells ● 2 electrons fit into the first energy level ● 8 electrons fit into the second energy level ● 8 electrons fit into the third energy level ● Valence electrons: the electrons on the outer shell ○ This is the only thing we care about ● The valence shell is what makes the electron stable and what makes the bonds ● Atoms with unpaired electrons in their outermost shell interact with other atoms to make sure they have 8 valence electrons ○ They donate, accept, or share electrons to eliminate vacancies ● Lewis dot diagrams are pretty important ○ To place the electrons you go counter clockwise, if theres more than 4, go one more time ● Two electrons on the same side are called a “lone pair” or just a pair ● An atom with equal numbers of protons and electrons has no net charge ● Ions (positive or negative) ○ Atoms that have gained or lost electrons ● Electronegativity ○ How much those atoms attract other electrons ● The periodic trend for electronegativity increases as you go to the right and as you move upwards ○ Fluorine is the most electronegative and Francium is the least electronegative ● Hydrogen bonds covalently (it does not ‘demand’ electrons)
● Bond types ○ Ionic - the positive negative stuff ○ Covalent - sharing ○ Hydrogen ● Hydrogen Bonds: form between a hydrogen atom and an electronegative atom, each with a separate polar covalent bonds. ○ Each have separate polar covalent bonds ○ Do not make atoms into molecules ○ Individually weak ○ Collectively stabilize structures of large molecules ● Suffixes ○ __ane -- single bond ○ __ene -- double bond ○ __yne -- triple bond ● Know the meth, eth, prop, bute, etc. sequence ○ Tells the number of carbons ● Cyclo - the rings of carbon ● Cyclohexene ■ Has a ring ■ 6 carbons ■ At least one double bond ● Non - Polar covalent bond ○ Atoms share electrons equally ● Polar covalent bond ○ Electrons are shared unequally ○ One end slightly negative, other slightly positive ○ Polar molecule has a separation of charge ● Oxygen does not have a formal charge, but it does have a slightly negative charge ○ δ negative ○
You've reached the end of your free preview.
Want to read all 8 pages?
- Fall '16
- Mr. Trembly
- Atom, Chemical bond