Chemistry Review Atoms, elements & Isotopes

How Big is an Atom?

How Many Cuts? Cut cm5.5"Child's hand, pockets Cut 27.0 cm2.75"Fingers, ears, toes Cut 33.5 cm1.38"Watch, mushroom, eye Cut cm.69"Keyboard keys, rings, insects Cut 6.44 cm.17"Poppy seeds Cut 81 mm.04"Thread. Congratulations if your still in! Cut mm.01"Still cutting? Most have quit by now Cut mm.002"Microscopic range, human hair Cut mm.006"Width of paper, microchip components Cut 181 micron.0004"Water purification openings, bacteria Cut 19.5 micron "Visible light waves Cut micron "Electron microscope range, membranes Cut micron "The size of an Atom!

I.Atoms A. the basic unit of matter B. matter is anything that takes up space and has mass C. all things are made of atoms D. microscopic … need special microscope to view million atoms lined up in a row would only measure 1 cm long

E. Atomic Structure/components 1. Subatomic particles: a. protons 1- positive charge 2- mass weight b. neutrons 1- no charge 2- mass weight c. electrons 1- negative charge 2- mass weight All atoms have the same amt of protons and electrons Atomic number - # of protons Atomic Mass - #p + #n

You can see an atom with your eyes? 1. True 2. False Countdown 10

An atom has weight 1. True 2. False Countdown 10

Which subatomic particle is located outside the nucleus of an atom? 1. Electron 2. Neutron 3. Proton Countdown 10

The positively charged particle in an atom the Countdown Electron 2. Neutron 3. Proton

Protons and ______ are found inside the nucleus. 1. Electrons 2. Neutrons 3. Protons Countdown 10

The negatively charged particle in the atom is the 1. Electron 2. Proton 3. Neutron Countdown 10

Which combination of particle and charge is correct? Countdown Proton: negative charge 2. Electron: positive charge 3. Neutron: negative charge 4. Neutron: no charge

II. Elements & Isotopes A. Element is a substance that cannot be broken down B. Elements are made up of lots and lots of the same kind of atom C. more than 100 elements known 1. represents with a single or 2 letters D. only about 2 dozen in living organisms 1. examples – Ca, O, H, C, N, P, K, S, Na, Li, Zn, Mg, Cu, Fe, Se, I, F Co, Al, Si, Br, Ar, Mn, Sr, Pb, V E. Essential Elements of Life: C H N O P S Ca K

F. Isotopes 1. atoms of the same element that have differ masses due to the differ number of neutrons on the nucleus a. example: Carbon -12 ; Carbon -13; Carbon – 14 b. all isotopes have the same chemical properties

G. Radioactive Isotopes 1. isotopes that give off radioactivity and have unstable nuclei 2. these isotopes break down at a consist rate after a period of time 3. although very dangerous, can be helpful a. Aging Fossils/Rocks b. Treat cancer c. Radioactive “tags” – trace substances d. PET scan (CT scan)

III. Compounds A. a substance made of 2 or more elements 1. example – H2O B. held together by chemical bonds C. main types: - ionic - covalent bond - hydrogen - van der waals

Isotopes weight the same. 1. True 2. False Countdown 10

Radioactive isotopes are good 1. True 2. False Countdown 10

Two or more different atoms are combined to form a 1. Symbol 2. Element 3. Isotope 4. Compound Countdown 10

In which if the following way do isotopes of the same element differ? Countdown In number of neutrons only 2. In number of protons only 3. In number of protons & mass 4. In number of neutrons & mass

D. Ionic bonds 1. formed when 1 or more electrons are transferred from 1 atom to another a. opposite charges attract to form an ionic bond (Na(+)) (Cl(-)) b. when atoms lose electrons, the atoms becomes positive c. when atoms gain electrons, they become negative 2. when an atom becomes positively or negatively charged, they become known as ions a. if positively charged known as cation b. if negatively charged known as anion

E. Covalent bonds 1. forms when electrons are shared between atoms 2. Two types a. polar covalent 1- unequal sharing due to size differences 2- example: H 2 O b. nonpolar covalent 1- equal sharing of electrons

F. Hydrogen Bonds Hydrogen bond is the weak attraction between δ + of H and δ- of O or N of a different molecule

G. Van der Waals Interactions 1. Electrons move creating weak positive and negatively charged regions (even if non- polar) 2. named after the scientist 3. can hold even large molecules together 4. geckos show this force a. climbing up the smoothest surface, geckos can hold on even with 1 toe b. a gecko foot is covered w/ half million projections

c. the projections are dived into 100s of tiny flat fibers designed to come onto contact with a surface at the molecular level d. van der waals forces form btwn the surface molecules and the gecko foot e. when a gecko wants to move it peels its foot off at angle then reapplies it elsewhere on the surface

A covalent bond is formed by 1. Transferring of electrons 2. Sharing electrons 3. Losing electrons 4. Gaining electrons Countdown 10

Ionic bonds are formed when 1. Transferring of electrons 2. Sharing electrons 3. Losing electrons 4. Gaining electrons Countdown 10

The gecko is an example of Countdown Covalent bonds 2. Ionic bonds 3. Hydrogen bonds 4. Van der Waals forces

When an atom loses electrons it becomes a ______ ion Countdown Positively charge 2. Negatively charged 3. Neutral

There are three types of covalent bonds 1. True 2. False Countdown 10

Polar covalent is the unequal sharing of electrons 1. True 2. False

IV. Representing Atoms A. Bohr Model (e cloud) 1. Use element or # protons/neutrons in nucleus 2. Surrounding by energy shells w/e a. 2 electrons in first shell b. 8 electrons in 2 nd c. 18 electrons in 3 rd shells

B. Lewis Dot Structures 1. Use element symbol 2. Use dots to represent 3. valence electrons only

The Bohr Model shows how many electrons the element has 1. True 2. False Countdown 10

The Lewis dot model shows all electrons an element has 1. True 2. False Countdown 10

Questions ASSIGNMENT: Review questions