HC ch3

Isotopes

Atoms of the same element that have different numbers of neutrons but same number of protons

1 amu =

1.67x10^-24

half-life

length of time required for half of the radioactive atoms in a sample to decay into a new element

steps of half life

1. List givens (half life, total time, initial mass)
2. Determine # of half lives in total time given
3.multiply mass of isotope by 1/2 for each half life

The _ of some isotopes are _ and when they decay they give radiation that causes _

Nuclei, unstable, electrons to be removed from atoms

This phenomena is _ and the radiation produced is _ radiation

radioactivity, ionizing

A nuclear reaction is a reaction that affects the _ of an atom

Nucleus

An _ nucleus wants to be _

Unstable, stable

Unstable nuclei undergo _ changes that _ their # of _ or _ in order to find _

spontaneous, change, protons, neutrons, stability

The total _ and _ must be equal on _ sides of the equation

mass number, atomic number, both

Five types of radiation

Alpha, beta, gamma, positron emission, and electron capture

alpha radiation

four nuclei emit from radioactive source, called alpha particles. Contains two protons and two neutrons and have a double positive charge. The symbol is 4He2.

equation for alpha radiation

238U92->234Th90 + 4He2

result of alpha radiation

Mass -4, atomic # -2

What happens in alpha decay?

Helium nucleus is emit

beta radiation

An emission resulting from the breaking apart of a neutron in an atom is called a beta positive. The symbol is 0e-1

Equation for beta radiation

14C6->14N7 + 0e-1

Result from beta radiation

Mass-0, atomic # +1

What happens in beta decay?

Neutron becomes proton and beta particle

Positron

A positron is a particle that has the same mass as an electron but had a positive charge, and is emitted from the atom during some kinds of radioactive decay. The symbol is 0e+1.

equation of positron

38K19->38Ar18 + 0e+1

Result of positron

Mass -0, atomic # -1

What happens in positron

A particle with a positive charge but same mass as an electron is emitted. A proton becomes a neutron.

electron capture

Neutron or electron capture an inner orbital electron is captured by the nucleus of its own atom. The inner orbital electron combines with a proton, and a neutron is formed. Symbol 0e-1.

equation for electron capture

106Ag47 + 0e-1 -> 106Pd46

Result of electron capture

Mass -0, atomic # -1

What happens in electron capture

a proton becomes a neutron and an electron is absorbed.

Gamma radiation

A high energy photon emitted by a radioisotope is called a game ray. The high energy protons are electro magnetic radiation. Symbol:y.

Equation for gamma radiation

230Th90-> 226Ra88 + 4He2 + y

Result of gamma radiation

Mass -4, atomic # -2

_ particles are the _ penetrating. _ rays are the _ penetrating. Paper will stop _; wood will stop _ and _; and lead or concrete will stop _, _ and some _

alpha, least, gamma, most, alpha, alpha, beta, alpha, beta, gamma

Alpha particle mass

4 amu

Alpha particle charge

+2

Beta particle mass

1/1837 amu

Beta particle charge

-1 charge

Gammma particle mass

0 amu

Game particle charge

0

symbol of alpha radiation

4He2

Symbol of beta radiation

0e-1

symbol for positron

0e+1

Symbol for electron capture

0e-1

Difference between beta and electron capture equations

Symbol comes on the left side of electron capture equation. Right side for beta.

What model did John dalton create

Solid sphere model

What did John Dalton come up with?

atomic theory, atoms of the same element are identical, atoms can't be created or destroyed, all matter is made up from atoms, atoms are joined separated and rearranged but never changed into atoms of another element

What was dalton wrong about?

all elements of the same type being identical and atoms being indivisible

What did JJ Thomson discover?

He discovered the subatomic particle called the electron, which was small and negatively charged.

What was JJ Thomson's model?

Plum pudding model

What was JJ Thomson's experiment?

Cathode Ray Tube where electron beam was shot and went to the positive side leading to the discovery of an electron

What did robert Millikan do?

His oil drop experiment measured the charge of an electron.

What is the charge of an electron?

1.602 x 10^-19 coulombs

What model did Ernest Rutherford create?

Nuclear model

What did Ernest Rutherford discover?

He discovered the nucleus

What experiment did Rutherford conduct?

Gold foil experiment, alpha particles were shot through a thin sheet of gold foil and some particles were deflected back while some passed through

What model did Niels Bohr create?

solar system model

What is a solar system model?

Made by Bohr, where the electrons are in a fixed orbit. Each level results in different power level.

When electrons move between _ energy is _ or _

levels, emitted, absorbed

What model did Ernest Rutherford create?

The proton model, protons are apart of large atoms nuclei

What model did Schrödinger and Heisenberg create?

The quantum mechanical and electron cloud model

What did Schrodinger do?

created the Quantum Mechanical Model proposed electrons orbit in levels with sublevels the orbit not circular. Electron location couldn't be predicted. Created a wave equation that determines likely hood of finding an electron in certain places

What did Heisenberg do?

He created his uncertainty principle which expresses the energy levels of electrons in atoms. Found that electrons live in fuzzy probability regions or clouds not distinct orbits.

What model did James Chadwick create?

The neutron model

What did James Chadwick discover?

He discovered the neutron by bombarding beryllium-9 with alpha particles, gave off high radiation with no charge, these rays when directed at wax displaces protons

What experiment did Chadwick conduct?

Bombarded beryllium-9 with alpha particles, gave off high radiation energy with no charge, rays displaced protons, showed neutrons existence

What did Marie Curie discover?

radioactivity

Nuclear reactions involve the _

Neutron

_ and _ and rearranged

Protons, neutrons

This releases a tremendous amount of _ called _

Energy, binding energy

Chemical reactions involve

Electrons

Chemical reactions _ to keep stability

Lose or share electrons

Nuclear reactions _ to maintain stability

lose protons or neutrons to become a new element

An unstable nucleus released energy r emitting _

Radiation

In nuclear reactions mass converts into

Energy

What is nuclear fission?

the splitting of an atomic nucleus into two smaller nuclei, releasing energy and two or three neutrons. This happens when an atom is bombarded with neutrons

How can we control neutrons in a chain reaction?

neutron moderation: slow down neutrons, water slows down
Neutron absorption: decrease # of neutrons, dense materials absorb

What is nuclear fusion?

the process of combining lightweight nuclei to make heavier nuclei accompanied by the release of energy

Where does nuclear fusion occur?

the sun's color

What is solar fusion?

Hydrogen nuclei fuse to make helium and two positrons. This releases energy.

What is the different between fission and fusion?

Fusion: two nuclei combine to create one
Fission: one nuclei splits to create two more

Positives and negatives with fusion

Fuels are inexpensive and available, hard to achieve high temperature to start, hard to contain once started

Difference between chemical and nuclear reactions

chemical involves electrons, nuclear involves the nuclei, chemical creates substances, nuclear creates elements, small amounts in chemical compared to nuclear

The _ amount of mass is changed into amazing amount of _

Small, energy

Use of radioactive elements

carbon dating, smoke detector, med

The _ is very hot

Core of a star

How is plasma formed?

when the temperature and pressure is continually raised until electrons are stripped away from the atom, resulting in positively charged nucleus and electrons

What is plasma?

Mixture of positively charged nuclei with free electrons

What happens to the positively charged nuclei?

They collide and combine to make a new element, this is fusion

Lost mass in fusion is created into _

Energy

This energy causes

The stars to glow and shine

Who used the cathode ray tube?

JJ Thomson

Who conducted the gold foil experiment?

Ernest Rutherford

Who decided that all atoms are indivisible?

John dalton

Who created the plum pudding model?

JJ Thomson

Who discovered the electron?

JJ Thomson

Who discovered neutrons

James Chadwick

Who discovered the nucleus

Ernest Rutherford

Who proposed the cloud model of the atom?

Heisenberg

Who proposed that all atoms of an element are the exact same?

John Dalton

Who measured the charge of an electron?

Robert Millikan

Who developed the solar system model?

Niels Bohr

Who conducted the oil drop experiment?

Robert Millikan