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| observations without numbers |
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| how close to the actual value a measurement is |
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| how close a set of values are to each other |
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| What is the definition of an atom? |
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Definition
| The smallest particle of an element that retains the properties of that element |
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| How does Dalton's atomic theory help to explain the law of conservation of mass? |
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Definition
| . Part of Dalton’s theory states that atoms cannot be created or destroyed in ordinary chemical reactions just arranged |
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| Explain Rutherford’s gold foil experiment. What did Rutherford discover about the structure of the atom? |
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Definition
| In the experiment, alpha particles (helium nuclei) were streamed toward a sheet of gold foil. Some of the alpha particles bounced off of the gold foil. This meant that they were hitting a dense, relatively large object, which Rutherford called the nucleus |
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| 66. Where are each of subatomic particles located in the atom? |
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Definition
| ? Protons and neutrons: nucleus; electron: electron cloud |
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| What is the charge on each particle? |
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Definition
| Proton - +1; neutron – 0; electron - -1 |
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| 67. Why is an atom electrically neutral |
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Definition
| Because the number of protons and electrons are the same and they have the opposite charge, so the positive and negative charges cancel out. |
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| 68. How do isotopes of an element differ? |
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Definition
| They have different number of neutrons (which makes their masses different) |
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the number of protons (what defines an element) and what the periodic table is organized by;
mass number the sum of the number of protons and neutrons for an isotope; |
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| the weighted average mass of the element, including all isotopes and their %abundance |
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| 71. An element is defined by the number of _ it has, also known as the _ _. |
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| 74. How many electrons can occupy any s sublevel |
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| 77. What can be said about the properties of elements in the same group or column in the periodic table? |
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Definition
| The elements within a group on the PT have similar reactivities because the have the same number of valence electrons and therefore the same ways of bonding |
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| 78. Where are the alkali metals on the periodic table? Alkaline earth metals? Halogens? Noble gases? |
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| 79. Where are the transition metals on the periodic table? |
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| In what “block” are they found? |
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Definition
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| 80. Where are the lanthanides and actinides on the periodic table? |
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| In what “block” are they found? |
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Definition
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| 81. Define valence electrons. Electrons located in the outermost energy level, they are the electrons that are involved in chemical reactions. Explain how you would find the valence electrons for an element and give an example. |
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Definition
| The number of valence electrons equals the number of electrons in the highest energy level (it also equals the group number for the s block and the group number -10 for the p block) |
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| Who is credited with developing the first periodic table? |
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| mendeleev's periodic table was arranged in order of increasing____ |
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| moseley made an adjustment to mendelee's table by arranging the elements in order of increasing___ |
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| what was mendeleev able to predict |
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| elements that had not yet been discovered |
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| why is mendeleev's table called periodic? |
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Definition
| the properties of the elemtens repeat ina regular pattern |
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| elements in a group or family of the periodic table will have similar |
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| a measure of the size of the atom: distance from the center of the nucleus to the edge of the electron cloud. |
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| how does atomic radius change going down a group? |
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Definition
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| how does atomic radius change going left to right? |
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| decreases across a period |
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| the amount of energy required to remove an electron from an atom |
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| how does ionizationg energy change going down a group? |
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Definition
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| how does ionization energy change across a periof left to right? |
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| how does electronegativit change going down a group? |
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| how does electronegativity change across a period left to righ? |
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| what is the most electronegative element on the periodic table? |
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| on what side of the periodic table do elements have more metallic character? |
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Definition
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| on what side are the nonmetallic |
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| what type of element tends to gain electrons to become stable? |
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Definition
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| what type of element tends to lose electrons? |
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| the electrons involved in the formation of a chemical bond are called____ |
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Definition
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| a chemical bond resulting from the attraction between positive and negative ions is called |
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| the chemical bond formed when two atoms share electrons is called? |
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| molecular compounds contain what types of elements? |
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| if the atoms that share electrons have an unequal attraction for the electrons the bond is called___- |
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| atoms tend to form bonds so that the number of electrons in the outermost energy levels is what? |
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| the elements in the ____ group satisfy the octect rule without following compunds |
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| contrast the 3 states of matter in terms of shape and volume ( definite or not? ) |
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solid- definite shape and volume
liquid- definite volume, not definite shape
gas- no definite shape and volume |
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| contrast the 3 states of matter in terms of how closely packed the particles are |
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Definition
solids-particles touching and fixed in place but vibrating.
liquid-particles are touching but can slide past each other
gases- particles are far apart and free to move around |
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| what are the two types of mixtures? |
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homogenous- no visible particles looks uniform throughout particles do not settle out of solution
heterogeneous-particles are visible/ non uniform appearance, particls can settle out, seperate. |
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| what are examples of homogeneous and heterogeneous? |
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Definition
homo- milk saline solution kool aid
hete- salad dressing, orange juice |
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| what are two types of pure substances? |
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Definition
compound-substance made up of two or more elements, has a fixed chemical formula and a specific set of properties.
element- simpliest form of matter, composed of 1 type of atom, found on the periodic table |
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| how can a mixture of salt and water be seperated? |
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| can a compound be seperated? |
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| yes by a chemical reaction |
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| can an element be seperated? |
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| no unless it undergoes a nuclear reaction |
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| determined by the reactivty of s ubstance |
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| can be determined without any chemical reaction taking place |
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| what are the five signs of a chemical reaction? |
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Definition
| precipitate formed, gas formed, light produced, energy change, permanent color change |
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| how can exothermic and endothermic reactions be identified? |
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exothermic releases energy
endothermic absorbs energy |
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| where are metals located on the periodic table? |
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| to the left of the staircase |
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| where metalloids and nonmetals located on the periodic table? |
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metalloids- are along the staircase
nonmetals-to the right of the staircase |
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| what are ionic compounds? |
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| compounds formed between a metal and a nonmetal |
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| what type of bond do ionic comounds have? |
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Definition
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| which type of ion comes first in an ionic compound formula? |
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| the positive ions which are the metals. |
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| compounds with two nonmetals |
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| what type of bond do molecular ions have? |
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| the elements of which group/family do not typically form bonds? why not? |
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| noble gases, because they already have 8 valence electrons |
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