Chapter 2.1-2.4 - Subatomic Particles

Thomson and his zesty cathode rays

• electricity travels the length of the tube in a beam of cathode rays (stream of electrons) pass through a hole in the center of the anode

• found mass to charge ratio, ratios of the particles was always the same

Millikan

discovered mass and charge

• xray removed electrons from N2 and O2, oil would fall and collide with and absorb electrons, becoming negative

• the drops rate of fall could be adjusted using charged metal plates, could calculate charges on drops

unit of fundamental charge for electrons

-1.602×10^-19 Coloumb

Mass to Charge Ratio —>

-5.686×10^-12 kg/C

Thomsons Plum Pudding Model

that electrons exist like raisons in a blob of positive charge

Radioactivity:

the spontaneous emission of high energy radiation and particles

Beta particles:

a particle emitted during radioactive decay and is equivalent in mass and charge to a high energy electron (penetrate better)

alpha particle:

a particle that is emitted during radioactive decay and is equivalent un mass and charge to a He nucleas.

Rutherford tests the plum pudding? DID IT WORK

bro no! many particles were detected directly opposite the emitter, some were deflected at large angles

• concluded that a tiny fraction of alpha particles encountered small regions of high positive charge and large mass

Anion

extra electron so negative

Cation

missing electron so positive

Unified atomic mass unit:

unit used to express relative masses of atoms and particles

By dividing the mass of any of the particles in kg by its mass in unified atomic mass units yields the result that…..

1u is equivalent to 1.66054 ×10^-27 kg

atoms with odd amounts of protons and neutrons can….

absorb and reemit tiny quantities of energy when placed inside magnetic fields

Isotope

atoms of an element contain the same # of protons but a different number of neutrons (have different mass numbers)

Nuclide:

specific isotope of an element

What is the correct isotope notation?

On the left: A(mass #) Z(atomic number) —> X element symbol

Atomic # + charge =

number of electrons

Periods:

the 7 horizontal rows

groups:

the 18 columns

Metals:

they conduct heat and electricity, malleable, ductile, shiny solids (except mercury)

Nonmetals:

poor conductors of heat and electricity, gases at room temperature, solids are brittle (Br is liquid at room temp)

Metalloids:

some properties of both, physical property of metals and chemical properties of nonmentals

Main group elements:

groups 1, 2 —> 13-18

Most common in universe

transition metals:

groups 3-12

Noble Gas

group 18

lanthanides

58-71a

actinides

90-103

All isotopes of the elements with atomic numbers above 83 are…

radioactive

radionuclide:

radioactive nuclide

they spontaneously emit high energy radiation/particles, and are transformed into other nuclides

Alkali metals:

group 1 elements: called this because when they and their oxides react with eater, they form alkaline (basic) solutions

Halogens:

group 17, form 2 element ionic compounds with the group 1 elements

Alkaline earth metals:

group 2, form ionic compounds with halogens with a ratio of cations to anions of 1:2 because all of the group 2cations have plus 2 charges

Chalcogens:

group 16

Average atomic mass:

weighted average of the masses of all the elements isotopes

natural abundance:

the proportion of a particular isotope relative to all the isotopes of that element in a natural sample

weighted avg atomic mass:

mx: a1m1 x a2m2 x …..

mass spectrometer:

ionize atoms and molecules and separate and detect their ions

precise natural abundance values

molecular mass:

the mass of 1 molecule of a compound (sum of the avg atomic masses of the atoms chemically bonded together)

formula unit:

smallest electrically neutral unit of an ionic compound

formula mass:

the sum of the average atomic masses of the cations and anions that makeup a neutral formula unit.