NOTES

CHAPTER 18

Section One:

protons and neutrons in nucleus electric field on outside

strong force is one of four basic forces in nature and about 100 times stronger than electric force strong force is short range and electric force is long-range

attracted strong force repelled electric force

Small nucleus is held together tightly Large nucleus not held together so tightly because forces only can act so much.

when nucleus is kept together by strong force it is stable when it is not it is unstable and radioactive

synthetic elements - have more than 92 protons

more than 83 protons - radioactive

1:1 is stable and 3:2 is stable anything close may be stable by anything too far or close to this amount of protons is radioactive

number if protons - atomic number

number of protons and neutrons - mass number

mass number minus atomic number equals number of neutrons

1896 Henri Becquerel discovered uranium salt

Marie and Pierre Curie discovered polonium and radium that were radioactive

tested results and came up with .1 g of radium

isotopes: same number of protons different number of neutrons

Section Two:

when unstable nucleus decays particles called nuclear radiation are emitted types of radiation are alpha, beta, and gamma radiation alpha and beta are particles gamma radiation is electromagnetic wave

alpha: massive particles lose energy quickly can be stopped by sheet of paper are least penetrating form of radiation damage can lead to illness or disease

transmutation: new element has atomic number of 2 less and mass number is 4 less than original

beta: caused by basic force called weak force one electron is lost mass number remains same damage as alpha can be stopped by sheet of aluminum foil is emitted when a neutron decays into a proton

gamma: most penetrating form have no mass and no charge and travel at the speed of light emitted from nucleus when alpha or beta decay occurs thick dense material can stop gamma rays produce fewer ions because of no electric charge

carbon dating: plant and animal remains uranium dating: rocks

Section Three: detect alpha, beta, and gamma rays using instruments tools detect ions produced from radiation

bubble chamber or cloud chambers: alpha and beta particles can be detected nuclear radiation causes electroscope to lose it's charge

age= (1.44)1n [1 + Nl/Nu]

Geiger counters use current to detect levels of radiation

background radiation is always around us soil, food, body

radon 55% inside body 11% x-rays 11% cosmic rays 8% rocks and soil 8% other 7%

largest source is form the alpha decay of radon gas

Section Four: fission: becomes unstable and splits into 2 releasing energy and neutrons

Energy joules = mass kg x speed of light m/s SQUARED E = mc 2

chain reactions can be stopped by using stuff that will absorb neutrons

Fusion: H-1 + H-2 = He-3 & energy great temperature needed (stars and the sun)

radioactive isotopes are used as tracers to locate various atoms or molecules in organisms

Radiation emitted by radioactive isotopes is used to kill cancer cells.

CHAPTER 19

Section One: A typical metal is a hard, shiny solid that due to metallic bonding is malleable, ductile and a good conductor.

Groups 1 and 2 are the alkali and alkaline earth metals which have some similar and some contrasting properities.

The iron triad, the coinage metals, and the elements in Group 12 are examples of transition elements.

The lanthanum's and actinides have atomic numbers 58 through 71 and 90 through 103.

Section Two: Nonmetals can be brittle and dull. They are also poor conductors of electricity.

As a typical nonmetal, hydrogen is a gas that forms compounds by sharing electrons with other nonmetals and by forming ionic bonds with metals.

All the halogens, Group 17, have 7 outer electrons and form covalent and ionic compounds, but each halogen has some properties that are unlike each of the others in the group.

The noble gases, Group 18, are elements whose properties and uses are related to their chemical stability.

Section Three: Groups 13 -16 include metals, nonmetals and metalloids.

Allotropes are forms of the same element having different molecular structures.

The properties of three forms of carbon - graphite, diamond, and buckminsterfullerene - depend upon the differences in their crystal structures.

The synthetic elements are short-lived. Expect for technetium - 43 and promethium -61, they have atomic numbers greater than 92 and are referred to as transuranium elements. These elements are found toward the bottom of the periodic table.