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CEM 141
Exam 1 Flashcards
| Question | Answer |
|---|---|
| scientific question : | testable or measurable |
| claim : | target of explaination |
| evidence : | data/scientific principle to support your claim |
| reasoning : | connection between your claim and evidence |
| scientific theory : | best available explanation of existing evidence, explains how and or why, can be proven false, can change over time |
| all things are made up of _________. | atoms |
| what part of an atom contains the most mass? | nucleus |
| what part of an atom contains the most volume? | electron cloud |
| which is the biggest? - atom - molecule - cell | cell ( molecule is made up of atoms, and a cell is a collection of molecules ) |
| what differentiates one element from another? | the amount of protons in the nucleus (atomic number) |
| a molecule contains _______ or ________ atoms. | two, more |
| difference between an element and a compound : | element - made up of the same atom compound - made of up multiple different elements with multiple different atoms |
| the original idea of atoms came from the ________. | greeks |
| macroscopic : | things we can see with our own eyes |
| what keeps atoms is constant motion? | energy |
| how are atoms of different elements different? | number of protons, masses, densities |
| true or false: a element (collection of atoms) has different properties than a single atom. | true |
| is it possible to have an atom of a compound? | NO compounds contain 2 or more types of atoms |
| true or false : atoms are composed of small indivisible, indestructible particles called atoms. | false they can be broken up |
| true or false : all atoms of an element are identical and have the same mass and propeties. | false there are isotopes |
| true or false : compounds are formed by combinations of atoms of 2 or more elements. | true this is the definition of a compound |
| which subatomic particle was discovered first? | electron |
| what is the name of JJ Thomson model for the discovery of the electron? | cathode ray tube |
| true or false : the type of metal the cathode was made of did not affect the behavior of the ray. | true |
| particle ray bent toward the ________ plate | positive |
| what is the evidence from Thomson experiment that all atoms contain electrons? | particles were identical regardless of the metal used for the cathode |
| alpha particle ________ if its same charge as nucleus | deflects (its repelled) |
| Rutherfords experiment showed : | atom is mostly empty space, the small dense positive nucleus in the center of the atom |
| neutrons are slightly ________ than protons | heavier |
| gravity is responsible for ________ between objects that have ________. | attraction, mass |
| electromagnetic force is responsible for ________ or ________ between objects that have electric ________. | attraction, repulsion, charge |
| when a ball is thrown into the air what force(s) are acting on the object as it is in the air? | gravity |
| what happens to the gravitational force of attraction as the mass of the interacting object increases? | the force increases |
| what happens to the gravitational force of attraction as the distance between the interacting objects increases? | the force decreases |
| the electromagnetic force is much ________ than the gravitational force. | stronger |
| if two objects have the same charge they ________. | repel |
| if two objects have opposite charges they ________. | attract |
| the force between charges can be modeled by using ________ law. | coulombs |
| if ________ charge object two the force increases. | increase |
| if ________ distance between objects the force decreases. | increase |
| both interactions of gravitational force and electromagnetic force follow an ________ law. | inverse square |
| if someone has a ball resting on their hand what force(s) are acting on it? | gravitational and electrostatic (gravity pulls is downward (attraction) and electrostatic pushes it upward (repulsion)) |
| changes in energy are caused by changes in ________. | forces |
| system : | part of the universe you are looking at |
| surroundings : | everything else in the universe |
| kinetic energy is the energy associated with ________. | motion |
| a ball is falling down, as the ball moves toward the ground what happens to the KE? | it increases (the ball is accelerating so the velocity increases) |
| potential energy is the energy associated with the ________ of objects in a field. | position of systems |
| a ball is falling down, as the ball moves toward the ground what happens to the PE of the system? | it decreases (the position of the object in the system between the ball and earth in the gravitational field) |
| when two objects are moving with a force PE ________. | decreases |
| when two objects are moving against a force PE ________. | increases |
| the ball is falling down, as the ball is falling what happens to the total energy of the system? | it remains the same |
| energy can be ________ from one object to another upon collision. | transferred |
| energy can be ________ from PE ---> KE. | transformed |
| if a system is isolated what will happen to KE as the PE changes? | it will have the opposite reaction (if PE increases KE will decrease, amount of energy must remain the same) |
| what is happening to the PE as 2 objects with the same sign move together? | PE will increase (working against the force) |
| properties of a solid : | definite shape and volume, can not be compressed |
| properties of a liquid : | takes shape of container, can move, definite volume |
| properties of a gas : | can be compressed, no specific shape or volume |
| to have solids and liquids atoms must ________. | stick together |
| dipole : | separation of charges within an atom |
| instantaneous dipole : | electron cloud can fluctuate momentarily creating a partial charge that only lasts for a moment. |
| induced dipole : | if it comes close to a dipole charges get pulled and this atom also becomes a dipole |
| LDF : | where two atoms are touching |
| how many atoms must be present for an LDF to exist? | two or more |
| the ________ coulombic interaction causes atoms to approach. | attractive |
| if atoms get to close and the electron clouds overlap then the ________ becomes dominant. | repulsive force |
| when the electron clouds overlap the PE ________. | increases |
| true or false : both gravitational and electrostatic forces are mediated by fields. | true |
| at the potential minimum the system is most ________. the attractive force = the repulsive force. | stable |
| why do atoms approach? (referring to dipoles) | the instantaneous dipole is inducing the neutral atom causing it to form a partial charge. |
| what do you have to do to break LDF's between atoms? | add energy (heat, change the temp) |
| when you change the temp of a system where does the energy come/go? | surroundings by collison |
| what about breaking of an attractive interaction between two atoms is ture? | energy is absorbed (breaking requires energy to go into the system) |
| when an element has more electrons is it easier or harder to form a dipole? | easier (the electron cloud is larger so it is "floppier") |
| the LDFs between atoms with more electrons are ________. | stronger (bigger electron cloud=bigger partial charge=stronger force) |
| would an atom with more electrons have a higher or lower melting point? | higher (when meting/boiling you are breaking LDFs and if it has more electrons the LDFs are stronger) |
| does an element with more electrons have a longer or shorter internuclear distance? | longer (it has a bigger electron cloud) |
| what info does the depth of the potential well tell you about the strength of the interaction? | the deeper the potential well the more energy would be required to get the atoms to separate (deeper the well the stronger the interaction) |
| what info does the position of the potential minimum along the x-axis give you? | the distance between the nuclei when the atoms are most stable (internuclear distance) |
| if the potential minimum is farther to the right will it have a larger or smaller atomic radius? | larger |
| if the well is deeper will is have a higher or lower boiling point? | higher (takes more energy to break LDFs) |
| when we remove energy from a system, it takes away from the ________ of the system and creates a _______. | total energy, molecule |
| atoms interact to form ________. | molecules |
| is a covalent bond stronger or is an LDF stronger? | covalent bond (needs a lot more energy for it to break) |
| intermolecular forces compared to bonds : | IMFs - relatively weak, occur between neutral molecules/atoms bonds - stronger, occur within molecules |
| when an atom melts ______ are broken | some LDFs |
| when an atom boils ________ are broken | all LDFs |
| when an atom gets to a very high temp ________ are broken | covalent bonds |
| what about forming a chemical bond is true? | energy is released |
| we use the ________ to allow us to connect from the molecular level to the observable macroscopic level. | mole |
| a mole : | 6.022 x 10^23 |
| mass of 1 mol in any substance is its ________ in grams. | formula mass |
| what happens to mass during a chemical reaction? | it remains the same (we are just rearranging, mass is CONSERVED) |
| 1 mol = ________ | number of molecules |
| to convert from mass to moles to mass we use ________. | molar mass |
| what properties ascribed by the Greeks do we still consider valid? | atoms are mostly empty space, and they are in constant motion |
| what experiment provided evidence that electrons are negatively charged? | cathode ray tube experiement |
| evidence from the cathode ray experiment that electrons are negatively charged : | beam of particles emitted from the cathode bent toward the positively charged plate |
| in the gold foil experiment where will the majority of the alpha particles go? | straight through the atom, because it is mostly empty space |
| true or false : it was found that in the gold foil experiment some of the particles would reflect off in different directions | true |
| what part of Daltons atomic theory did Thomson cathode experiment prove to be false? | all atoms are indivisible and indestructible |
| true or false : a nitrogen molecule is made of the same type of atoms | true |
| when a covalent bond between two atoms is formed energy is ________ and a ________ is formed. | released, molecule |
| why was the electron the first subatomic particle to be discovered? | they are on outside of an atom so it is easier to remove them, along with the fact they have a negative charge and easier to detect and can be manipulated by electromagnetic fields |
| description of Thomson's proposed atomic structure : | a positive "sphere" with negative charged embedded in it |
| description of Rutherford's model of the atom : | a positive nucleus with orbits around it containing electrons. |
| what did Rutherford discover? | that there is a positive nucleus within the atom |
| percent yield=________ yield / ________ yield. | actual, theoretical |
| true or false: the limiting reactant is whichever element produces more of the product from its starting amount. | false it is whichever product produces less |
| remaining amount of the excess product = ________ amount - ________ amount. | starting, used |
| what do you use to convert from moles of a molecule to grams of the same molecule? | molar mass |
| what do you use to convert from moles of one molecule to moles of another molecule? | stoichiometric ratio |
| percent yield : the actual amount comes from ________, and the theoretical amount comes from ________. | experiment, calculation |
| when a molecule has a ________ boiling point its potential well is deeper. | higher |
| why does adding thermal energy to a molecule make it change from a liquid to a gas? | it is transferred upon collision which increases the KE, when they have enough thermal energy they are able to overcome the attractive force and move apart. |
| electrons can be manipulated by _______ and ________ fields. | electrical, magnetic |
| when a bond is attractive bond is broken energy would transfer from the ________ to the ________. | surroundings, system |
| why is a atom with a higher boiling point father on the x-axis? | because it has larger electron clouds so when those atoms come together there nuclei will be farther apart. |
Created by:
mccurdyo
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