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an interpretation/a possible explanation of why someething happens (never become laws)
a natural observable phenomenon or event
a mixture of elements that have metallic properties
Hydrogen - H
Oxygen - O, etc.
What are the five main parts of Dalton’s Atomic theory
1. Elements made of atoms
2. Atoms of the same element are identical
3. Atoms of different elements combine to make compound
4. Atoms are indivisible in the chemical process, just changes the way atoms are grouped
5. The atoms of each element are different from atoms of another element
What is meant by the term chemical formula?
A formula showing what elements (and how many of them) are in a given compound
Describe Thompson’s experiment and what he discovered.
The plum pudding model refers to Thompson’s idea that at atom was a ball of positivity with little negative particles floating in it.
Right: there are small negative particles now called electrons
Wrong: there is really space between the electrons and a positive center, not one big positive particle with small negative ones inside it
Describe Rutherford’s Gold Foil experiment and what he discovered from it.
He shot alpha particles at a sheet of gold foil, most of these particles were deflected by the electrons, but some went straight through. This showed that atoms cannot be solid things, there must be space. This led to the discovery of the nucleus
Describe the modern atomic theory.
There is a solid center (nucleus) made of protons and neutrons (about the same size) and electrons (MUCH smaller than protons and neutrons) are located in the electron cloud around the nucleus
If all atoms are composed of protons, electrons, and neutrons, why do different atoms have different chemical properties?
o Different atoms have different numbers of protons and electrons (electrons are the ones that really matter).
What is the single most important factor in determining an atom’s chemical properties?
Electrons are the most responsible for the chemical properties.
Define and distinguish between isotopes, atomic number and mass number.
How did the discovery of the neutron lead to the concept of isotopes?
The neutral charge changing does not affect the atom’s identity at all, only its mass number. When they discovered the neutron, they discovered that the number of neutrons was not always the same in atoms of the same element and they called those with different amounts isotopes (Chadwick)
How does the fact that isotopes exist change Dalton’s model?
Dalton said that all atoms of the same elements are identical, that had to be changed to all atoms of the same element have the same number of protons and electrons, but can have different amounts of neutrons.
Why does our modern periodic table retain Mendeleev’s original arrangement scheme?
Because he arranged them in the best way possible, having them grouped by similar properties.
vertical columns; elements with similar chemical properties
rows of the periodic table
Ductility (can be pulled into wires)
touching the stairs; have properties of metals and nonmetals
an atom or group of atoms with a positive or negative charge from loosing or gaining electrons
How does knowing the ions in an ionic compound allow us to determine the chemical formula of the compound?
It allows us to know how many of each ion is needed to obtain a neutral compound
Describe Rutherford’s atom. What is wrong with Rutherford’s model? What is right?
His model contained a positive center and electrons with space in between. What is right is the positive center and the electrons with space in between. What was wrong is that there is no explanation of the electrons.
What does the behavior if light have to do with atomic theory?
Light behaves as a stream of particles and as energy, and atoms have particles and energy.
What is the relationship between wavelength and frequency of light and the energy transmitted?
Why do we see colors when salt solutions are burned?
The electrons of salt atoms are excited from the heat of the fire when the electrons return to the ground state, they give off energy that we see as light.
What does the term quantized mean?
Quantized means that electrons can only absorb certain amounts of energy and can only give of specific colors of light.
Why do scientists think the energy in an atom is quantized?
When electrons are excited they only give off specific colors of light (containing certain amounts of energy) showing that in can only take in those same amounts of energy
Describe the Bohr model of the atom. What is wrong with the Bohr model? What is right?
Bohr’s model consists of a nucleus and possible orbit routes for the electrons. What is right is that there are different levels where electrons are most likely to be found. What is wrong is that electrons do not travel in set orbits. His model only words for hydrogen.
Describe the wave mechanical model of the atom.
It is that same as Bohr’s model except for electrons move within orbitals. Not orbits.
What is the difference between an orbit and an orbital? Describe the four different kinds of orbitals.
4s 4p 4d 4f
3s 3p 3d
For hydrogen, what is the relationship between the principal level and the number of sublevel in each level?
Principal level= number of sublevels (for hydrogen)
Be able to draw an orbital diagram for the first 36 elements on the periodic table.
An orbital diagram is the box thing. Where each level gets a box. Draw the up arrows first, then going back to fill in the down arrows once each sublevel is filled with up arrows
Be able to write the electron configuration for any element on the periodic table that follows the general pattern.
Nearest noble gas: He
Goes into the 2p orbitals (2 in)
nfiguration: [He] 2s23p2
Distinguish between metals, nonmetals and metalloids in terms of their electron arrangements
Metals tend to lose electrons and nonmetals tend to gain electrons. Metalloids to the left of the stairs act like metals in that they lose electrons and metalloids to the right act as nonmetals in that they gain electrons.
Describe how atomic size changes across a period and down a column on the periodic table.
As you go across a column size gets smaller, and as you go down a column size gets bigger.
Describe how ionization energy changes across a period and down a column on the periodic table.
As you go across a period ionization energy gets bigger (it takes more energy to ionize). To the right of the stairs as you go up ionization energy gets bigger, and to the right as you go down ionization energy gets bigger
What is a chemical bond?
The force that holds two or more atoms together and makes them function as a unit.
How do atoms form ionic bonds?
Ionic bonds are bonds between metals and nonmetals. The opposite charge brings them together.
How do atoms form covalent bonds?
Covalent bonds are formed when two atoms share electrons.
What is electronegativity?
The tendency of an atom to attract shared electrons to itself. [The higher the atom’s electronegativity the closer shared electrons will be when it forms a bond.]
What is a polar covalent bond?
A polar covalent bond is when one atom hogs the shared electrons because it has a higher electronegativity.
Provide an example of compounds bonded each of the following ways: ionic bond, covalent bond and polar covalent bond.
What is a dipole moment?
A line (that looks like a plus at one end and an arrow at the other) that shows the center of positivity (the plus side) and a center of negativity (where the arrow points)
Wat rule helps us determine the most stable electron configuration and charge of a particular ion?
Main group metals loose enough electrons to have the same configuration as the previous noble gas and nonmetals gain enough electrons to have the same configuration as the next noble gas.
Why are chemical compounds always neutral?
All chemical bonds contain one cation and one anion and having positive and negative charges makes the compound neutral.
Given different metal/nonmetal pairs, be able to predict the ionic formula of the compound their ions will form.
What is a polyatomic ion?
An ion with more than one atom
Describe the duet and octet rules of the Lewis Structure
Octet rule: applies to all other elements except hydrogen and a few other exceptions; all atoms in a bond must have 8 electrons (both electrons in each bond are counted.)
Besides duets and octets, what is the other number to keep in mind when drawing Lewis Structures?
The number of valence electrons you have to start with. The total amount of electrons in the Lewis Structure cannot be more than the amount of valence electrons you began with.
Explain what is meant by resonance.
Resonance is when a Lewis Structure can be written more than one way correctly.
Identify some exceptions to the octet rule and how to tell if a compound will be an exception
Boron is an exception to the octet rule. Any compound with an odd number of valence electrons will be an exception to the rule.
Distinguish between molecular structure and geometric structure of a molecule.
Molecular structure is the three dimensional arrangement of atoms in a molecule and geometric structure is the shape of the molecule.
Explain how the VSEPR Model is used for predicting molecule shapes (geometry)
Lone pairs of electrons a put as far away as possible. The shape that must be made in order for them to be as far apart as possible is the molecule’s shape.
Give an example of molecules that exhibit each of the following shapes: linear, bent, trigonal planar, tetrahedral and trigonal pyramid.
Be able to associate the characteristic bond angles with the different geometries of molecules
How are double and triple bonds treated in the VSEPR Model?
They are treated the same as single bonds
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