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Int. Science

Unit 3

What is Latent Heat? -Phase change that always absorbs or releases energy -Quantity of heat associated with a phase change which is not associated with a temperature change -Quantity of heat (Latent refers to hidden)
What are some common properties of matter? MASS (quantity) VOLUME (space matter occupies) DENSITY (ratio of mass per volume) SPECIFIC GRAVITY (density ratio with water’s density)
What is mass? measure of the inertia of the object. amount of matter present in an object. independent of the force of gravity. mass is measured in kilograms. differs from weight which is a downward force, the gravitational force acting on the object.
What is volume? the size. how much space something occupies. volume can be obtained by measuring; length x width x thickness (or height) or by displacement (with water) in milliliters units are typically cm3 or mL.
What is density? a ratio of the mass per unit volume. density = mass/ volume obtained by dividing the one number and its’ unit by another number and its’ unit. if matter is distributed throughout its volume, the ratio will remain the same.
What is specific gravity? ratio between the density of the substance and the density of some standard substance. the standard used is usually water for solids and liquids can be used to classify a substance
What is the basis for the kinetic molecular theory? all matter is made up of atoms atoms are not divided, created, nor destroyed during any chemical or physical change. different phases of matter have different molecular arrangements & average speeds of molecules. solid, liquid and gas
What are the characteristics of a solid? have definite shapes and volumes molecules are at fixed distances molecules are bound by strong cohesive forces. molecules of solids do vibrate hardness is the resistance of a solid to forces that tend to push its molecules further apart.
What are the characteristics of a liquid? molecules are not confided to an equilibrium position as in a solid. molecules are still close together, still have cohesive forces, but not as strong as a solid. liquid has a definite volume, but no definite shape. liquid molecules flow.
What are the characteristics of a gas? composed of molecules with weak cohesive forces acting on them. molecules are far apart. molecules move freely in a constant, random motion that is changed by collisions. have neither fixed shape or fixed volume.
How do phase changes take place? Adding or removing heat absorption or release of another form of energy three major phases changes involve solid & liquid; liquid & gas and solid & gas.
What is heat? Measure of the internal energy that has been absorbed or transferred from one body to another.
Boiling The temperature at which the pressure of a liquid is equal to atmospheric pressure.
Pressure Force per unit area.
What is a calorie? Or Calorie? The amount of energy (heat) needed to increase the temperature of 1 gram of water 1 degree Celsius Kilocalorie- ……1 kilogram of water…..
What does phase change have to do with energy? Freezing point or melting point depends on the direction of the phase change Boiling and condensation points are the same temperature Freezing and condensation release energy; melting and evaporation absorb energy
Where is the latent heat? Latent heat of fusion is involved in solid to liquid phase change For water = 80.0 cal/g Latent heat of vaporization is involved in a liquid gas phase change For water = 540.0 cal/g
What is specific heat? a variable that effects energy transfer. it is amount of energy (or heat) needed to change the temperature of 1 gram of a substance 1 degree Celsius. is related to the internal structure of a substance. water has a specific heat of 1.0 cal/gCo
What was the original paradigm regarding atomic theory? 4th century- idea of atom (indivisible particle) / minority view 1600s- Robert Boyle- defined an element as a simple substance that could not be broken down any further. 1800s- John Dalton -atoms as indivisibl
How did John Dalton change paradigms? ancient Greek idea of hard, indivisible atoms was paradigm. Dalton noticed that certain elements always combine with other elements in fixed ratios (H2O) . therefore whole atoms must combine to make the compound. elements must be made of atoms.
What is the atomic theory? All elements are composed of atoms. All atoms of an element are identical and different from atoms of other elements. When elements and compounds react, individual atoms of elements react in a simple whole-number ratio. gained WIDE acceptance (paradi
What are protons? carry a + charge located in the nucleus of the atom have a mass of one a.m.u. each element has an atomic number which is their number of protons
What are neutrons? have no charge associated. number of neutrons varies depending on the atom (within an range) of an element. very significant in radioactive elements neutrons have a mass of 1 a.m.u. are located in the nucleus of an atom.
What are isotopes? Deal with the nucleus Isotopes vary in the number of neutrons within an atom. EX: Carbon 12 vs. Carbon 14 Carbon 12 has 6 protons and 6 neutrons in nucleus Carbon 14 has 6 protons and 8 neutrons!
What are electrons? carry a negative charge attracted to + charge of proton move around atom in different orbitals (volumes of space) around the nucleus. in energy levels around the nucleus electron number and arrangement is key to the interactions of atoms
What is the Bohr atom? An electron can revolve around an atom only in specific allowed orbits. If it stays in the orbit, the electron doesn’t emit energy. An electron gains or loses energy only by moving from one allowed orbit to another. hydrogen atom has a “ground state
What are ions? Atoms are usually neutral – same number of protons & electrons electrons can also be donated to other atoms electrons can also be gained from other atoms=result is an imbalance of charge 2 many electrons/protons(=)- ion 2many protons/electrons(=)+ io
What are molecules? a group of atoms held together by a covalent (sharing of electrons) bond is a molecule. Electrons can be shared by atoms equally (nonpolar) covalent bond NOT equally (polar) covalent bond sharing can be multiple bonds!
Ionic bonding gain or loss of electrons
Covalent bonding sharing of electrons equally (non polar) such as H2.NOT equally (POLAR), such as H2O.
Hydrogen bonding (intermolecular) weak bond of attraction of partial charges
What are ionic bonds? formed when atoms transfer electrons to achieve the noble gas electron arrangement. electrons are given up or acquired in the transfer, forming + or - ions. the electrostatic attraction between the ions forms ionic bonds.
What are covalent bonds? result when atoms achieve the noble gas electron structure by sharing electrons. generally are formed between the non-metallic elements on the right side of the periodic table. can be equally shared (nonpolar) can be unequally shared (POLAR)
What are intermolecular bonds? forces of interaction between molecules. ex: hydrogen bonds where partial + end attracts partial - end of another molecule. weak attractive intermolecular forces. ex: the attractive force which holds compounds together in ionic bonding.
What are hydrogen bonds? the unequal covalent bond within some molecules results in a partial + end of the molecule and a partial - end. A hydrogen bond is a WEAK bond between the hydrogen end (+) of a polar molecule and the (-) end of a second molecule.
What contribution did Mendeleev make to chemistry scheme(1869) was based on chemical properties and atomic weights. predicted that elements would be discovered to fill the gaps in his table and predicted the physical and chemical properties of elements yet to be discovered
What is the periodic law? meant to help interpret easily the periodic table. an element is identified in each cell with its chemical symbol. the number above the symbol is the atomic number of the element. the number below the symbol is the rounded atomic weight of the elemen
What are metals? are elements that lose electrons to form positive ions. therefore are elements with one , two or three outer electrons to lose.
What is a nonmetal? elements that gain electrons to form negative ions. elements with five to seven outer electrons that tend to acquire electrons to fill their outer orbitals.
How is chemistry and life connected? On Earth, only living cells can make molecules such as : carbohydrates lipids proteins nucleic acids
How were cells first noticed? Galileo Galilei was first to see cells within a simple microscope. Robert Hooke gave the name cell. Anthony van Leeuwenhoek constructed microscopes and viewed “animalcules” moving. Matthias Schleiden and Theodor Schwann - cell theory
Who was Robert Hooke? Robert Hooke lived at mid seventeenth century. curator of instruments at Royal Society of England. sliced cork from a mature oak tree was looking at walls of dead cells (cork) when termed word cells. saw other cells “filled with juices”.
What is the cell theory? All organisms are composed of one or more cells. The cell is the smallest unit having the properties of life. Life arises directly from the growth and division of single cells.
What defines a cell? plasma membrane which makes the boundary of the cell with the outside environment DNAcontaining region where molecules can copy or read the hereditary instructions. cytoplasm where all else is located.It is semi-fluid and has particles,filaments and ev
What is the function of the cell membrane? regulates cell size. provides a major mechanism for moving materials into and out of the cell. must respond to the environment the cell is immersed in. serves as regulatory mechanisms of living organisms to respond to the environment.
What is the cell membrane like? it’s of a fluid quality, consisting of proteins and phospholipids. Phospholipids regulate water movement. phospholipids have a hydrophillic “head” and two hydrophobic “tails” . Determine if polar or nonpolar molecules can move across.
What does the cell membrane do? Proteins serve as transport molecules moving other molecules in or out. or as receptors which can bind with other molecules and make cellular changes or as recognition proteins to identify the cell or as adhesion proteins to help like cells stay toget
What is diffusion? is the movement of materials from an area of higher concentration to an area of lower concentration a physical process,caused by KE does not require active biological processes given enough time,like any physical system goes to equilibrium,with equal #
What is osmosis? is the movement of water across a cell membrane is caused by kinetic energy, is “water diffusion” across a membrane. As diffusion, it goes to equilibrium, so that given enough time, an equal number of molecules of water are moving across the membrane a
What are cell organelles? in the cells of plants and animals there are organelles. internal, membrane-bound sac that serves a special function for the cell. nucleus ribosomes mitochondria cytoskeleton
nucleus DNA/hereditary function
ribosomes making proteins
mitochondria ATP/ energy production
cytoskeleton cell shape and movement.
Prokaryotic cells bacteria,DNA is not enclosed within nucleus.
Eukaryotic cells have true nucleus,have organelles for specific functions
What is DNA? Discovered in 1953 contains only four types of nucleotides (building blocks). A nucleotide is a 5 carbon sugar (deoxyribose in DNA), a phosphate group and a nitrogen containing base: Adenine (A) or Guanine (G) Thymine (T) or Cytosine (C)
What is the structure of DNA ? the bases pair together: A = T G = C along two strands of DNA twisted in a helix. the order of base pairs gives information to the cells as to proteins to be built. They determine our traits.