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The flashcards below were created by user
MrsLuthor
on FreezingBlue Flashcards.
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Define: Qualitative Analysis
Testing an entity to determine the chemical contituants - what's in it?
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Define: Quantitative Analysis
Measurment of the quantity of a chemical entity - how much of something is in it?
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Define: Conductivity
The ability of a substance to conduct electricity, a physical property of matter.
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Define: Electrolyte
A compound that, when dissolved in water, produces a solution that conducts electricity.
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Define: Non Electrolyte
A compound that, when dissolved in water, does not create a solution that conducts electricity.
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Define: Octet Rule
Atoms gain or lose electrons in their outer most shells in order to attain a noble gas configuration.
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Define: Ion
An atom, or group of atoms, that has lost or gained one or more electrons.
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Define: Anion
An atom that carries an overall negative charge because it has more electrons than protons.
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Define: Cation
An atom that carries an overall positive charge because it has more protons than electrons.
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Define: Valence Electrons
Electrons found in the outermost shell of an atom.
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Define: Lewis Symbol
A diagram composed of a chemical symbol and dots, depicting the valence electrons of an atom.
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Define: Monatomic Ions
An ion that is composed of only one atom.
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Define: Polyatomic Ion
An ion that is composed of two or more atoms.
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Define: Ionic Bonds
The bond that results from the electrostatic force of attraction that holds positive and negative ions together.
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Define: Ionic Compound
A compound that consists of cations and anions held together by ionc bonds.
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Define: Ionic Crystals
A solid that consists of large number of cations and anions arranged in a repeating 3D pattern.
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Define: Formula Units
The smallest amount of a substance having the composition given by its chemical formula.
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Define: Atom
Small indivisible particles that have all the properties of the element they make up.
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Define: Element
A substance comprised of only one type of atom.
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Define: Isotopes
An atom that contains the same number of protons but a different number of neutrons.
ex: Cl-35 and Cl-37 are two naturally occurring isotopes of Cl. Both have 17 protons but Cl-35 has 18 neutrons while Cl-37 has 20 neutrons
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Define: Radioisotopes
Radioactive isotopes.
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Democratus - 2000BC
First to suggest that all matter is composed of tiny particles - atoms
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Dalton - 1804
"Billiard Ball Model"
- Elements are compost of identical indivisible atoms.
- Discovered subatomic particles showed that atoms were not indivisible.
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J.J. Thomson - 1900
"Raisin Bun Model" or "Plum Pudding Model"
Revised Dalton's model
- An atom can be described as a sphere of positive electricity in which negative electrons are embedded like raisins in a bun.
- Most of the mass of the atom is associated with the positive electricity.
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Rutherford - 1912
"Gold Foil Experiment"
- Atom has a nucleus in which its positive charge (protons) & mass are concentrated.
- The majority of the atom's volume would be empty space occupied only by moving negatively charge electrons.
- - The existance of uncharged particles (neutrons)
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Rutherford's Gold Foil Experiment
- Experiment:Shot a beam of positively charged subatomic particles of radioactive Polonium (Po) at a piece of gold foil contained within a circular florescent screen.
- Observed:
- Majority of protons passed through the gold foil uninfluenced, but 1 in every 10,000 experienced some kind of change in their path of travel. Thus, since some of the protons were deflected, there must be an area in the atom with a large positive charge (the nucleus)
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Bohr - 1913
"Orbit Model" or "Solar System Model"
- Carried out the flame test of the elements & explained that the different colours that resulted were due to the position of the electrons around the nucleus of the atoms.
- Electrons curcle the central nucleus in orbits (energy levesl) called shells.
- Each shell is a different distance from the nucleus.
- - Each shell has a maximum number of electrons that it can hold.
- 1st: 2
- 2nd: 8
- 3rd: 8
- 4th: 18
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Quantum Mechanical - 1920s
Mostly supports Bohr except:
- Electrons do not exist in fixed orbits / do not have a fixed or definite path. May exist anywhere within an electron cloud.
- Determining exactly where an electron will be at any given moment is very difficult and can only be theorized using mathematical equations.
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Structure of the Atom
Three types of particles:
- Protons:
- ( + ) or ( p )
- - Found in the nucleus (center) of the atom & have a charge of +1.
- - Particles are very dense and have a large mass compared to electrons.
- Neutrons:
- ( 0 ) or ( n )
- - Found in the nucleus of the atom and have a charge of 0.
- - Have the same mass as protons.
- Electrons:
- ( - ) or ( e )
- - Found in shells or orbits surroundign the nucleus and have a charge of -1.
- - Have a small mass.
- - In a neutral atom, are equal to the number of protons in the nucleus.
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Atomic Number
- Makes the element unique & is equal to the number of protons in the nucleus.
- In a neutral atom, it is also equal to the number of electrons in the shells.
- - In the periodic table, this number is usually found in the upper right corner of the element box (whole number)
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Mass Number
- Is equal to the number of protons and neutrons combined (p + n = mass)
- Usually found in the bottom of the element box as a decimal.
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AMU
Atomic Mass Unit - unit of measurement
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