Chemistry Matter and Change Chap 3 and 4

Matter that has a uniform and unchanging composition is called a

Substance

 

Salt & Pure Water are Substances

 

Salt Water and air are not

Changes to a substance that do not change its composition are known as
Physical Changes
The temperature and pressure at which a substance undergoes a phase change is a
Physical Property
A change that involves one or more substances changing into new substances is called a

chemical change

 

Crushing the grapes is a physical change

 

Fermenting the grapes into wine is a chemical change

What does the Law of conservation of mass state
Mass is neither created nor destroyed during a chemical reaction
A combination of two or more pure substances in which each pure substance retains its individual chemical properties

Mixture

 

Salt & Water

Sand & Water

 

A mixture that does not blend smoothly throughout and in which the individual substances remain dinstinct.

 

Heterogeneous Mixture

 

 

Hetero means different

 

Sand and Water

A mixture that has constant composition throughout where the substances are equally distributed.

 

 

Homogeneous Mixture or Solution

 

Homo means same

 

salt & water

A separation technique that is based on differences in the boiling points of substances.  Involves heating a mixture until the substance with the lowest boiling point turns to a vapor and is condensed and collected outside the mixture.
Distillation
A technique for separating mixtures that uses a porous barrier that only blocks one part of the mixture but allows the other to pass.
Filtration
A separation technique that results in the formation of pure solid particles from a solution containing the dissolved substance.
Crystallization
Separation technique that separates the components of a mixture on the basis of the tendency of eac to travel across the surface of another material.
Chromatography
What is an element
A pure substance that cannot be separated into simpler substances by physical or chemical means
A combination of two or more different elements that are combined chemically
Compound
Law of definite proportions

Regardless of the amount, a compound is always composed of the same elements in the same proportion by mass.

 

The mass of all the individual components of a compound are added together to get the mass of the compound.

What is the charge and composition of a Proton
A component of an atom that has a +1 charge and consists of 2 Up Quarks and 1 Down Quark

An Up Quark has what charge?

 

A fundamental particle with a +2/3 charge that is a component of Protons and Neutrons
A Down Quark has what charge?
A fundamental particle with a -1/3 charge that is a component of Protons and Neutrons
What is the charge and composition of a Neutron
A component of an atom that has a 0 charge and consists of two Down Quarks and one Up Quark
What is the charge and composition of a Electron
A fundamental particle with a -1 charge that is a component of an atom
The number of protons in an element or atom determines its
Atomic Number
The number of Neutrons in an atom determine its

Isotope

 

It also determines the stability of the atom

The mass of all the protons and all the neutrons in an atom are added to find its
Mass Number

Atomic Mass Units

amu

The mass of protons, neutrons, and electrons are measured in 

 

This measurement is 1/12 the mass of Carbon 12 atoms and is approximatly equal to the mass of 1 proton

The atomic mass of a particular atom is

the weighted average mass of all the isotopes of that element.

 

(Isotope #1)(Percent abundance of Isotope #1) + (Isotope #2)(Percent abundance of Isotope #2)

Formula to find the Percent abundance of an isotope when you only know the Atomic Mass average and the atomic mass of each of the isotopes
=Isotope#1(X) – Isotope#2(1-X) = Atomic Mass Average
Reaction in which one element changing into another element
Nuclear Reaction
Unstable atoms gain stability by losing ____________
Unstable atoms gain _________ by losing energy
Alpha Radiation
type of radiation released during radioactive decay that has a +2 charge and consists of 2 Protons & 2 Neutrons
Two Types of Beta Radiation

Beta Minus Decay ?

type of radiation released during radioactive decay that has a -1 charge and consists of 1 electron & 1 antineutrino

 

Beta Plus Decay ?+

type of radiation released during radioactive decay that has a +1 charge and consists of 1 Positron & 1 Neutrino

 

 

What is Gamma Radiation

type of radiation released during radioactive decay that has NO charge and consists of high energy high frequency photons.

 

It is an electromagnetic radiation, like X-rays

 

Radioactive primordial nuclides found in the Earth are

residues from ancient supernova explosions which occurred before the formation of the solar system. They are the long-lived fraction of radionuclides surviving in the primordial solar nebula through planet accretion until the present.

 

The naturally occurring short-lived radiogenic radionuclides found in rocks are the daughters of these radioactive primordial nuclides. Another minor source of naturally occurring radioactive nuclides are cosmogenic nuclides, formed by cosmic ray bombardment of material in the Earth’s atmosphere or crust.

What is Nuclear transmutation

conversion of one chemical element or isotope into another. In other words, atoms of one element can be changed into atoms of other element 

 

This occurs either through nuclear reactions (in which an outside particle reacts with a nucleus), or through radioactive decay (where no outside particle is needed). 

What occurs during Beta Minus Decay ?

A neutron overabundance creates instability.

 

Inside a Neutron a Down Quark changes to an Up Quark which changes the Neutron into a Proton and creates an antineutrino and an electron which are both released from the atom to maintain a conservation of electric charge so the element stays neutral.

 

this causes the element to become an element one place higher on the atomic chart.

 

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What occurs duing Beta Plus ?+

A neutron shortage creates instability.

 

Inside a Proton an Up Quark changes to an Down Quark which changes the Proton into a Neutron and creates a neutrino and an positron (an electron with a positive charge)  which are both released from the atom to maintain a conservation of electric charge so the element stays neutral.

 

this causes the element to become an element one place lower on the atomic chart.

 

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What occurs during Alpha Decay

Alpha decay is one process that unstable atoms can use to become more stable.  Occurs in very large nucleuses (larger than lead)

During alpha decay, an atom’s nucleus sheds two protons and two neutrons in a packet that scientists call an alpha particle.

Since an atom loses two protons during alpha decay, it changes from one element to another. For example, after undergoing alpha decay, an atom of uranium (with 92 protons) becomes an atom of thorium (with 90 protons).

The element reduces by two places on the periodic table

 

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