Unit 1: Review Flashcards
Define a “Hypothesis”
A hypothesis is a tentative explanation
Define a “Law”
A law summarizes related observations, but does not explain them
What are the 3 steps of scientific method?
Observation ➡️ Hypothesis ➡️ Test
Define a “Theory”
Explains parts of the universe, makes predictions about how it will react under given circumstances, hypothesis that have held up under rigorous testing
What must a theory be?
A theory must be falsifiable; it must be possible to prove it wrong
(ie: good “energies” emitted make people feel nice: there is no way to potentially disprove this because “energies” is not a measurable quantity)
1000 trials proving a theory true
And 1 trial proving the theory false
Is the theory proven or disproved?
Disproved, a single trail proving the theory false, makes the theory disproved.
What 3 things make a theory more or less credible?
Whether it makes small or risky predictions, whether few or many trials to disprove it have been conducted, and whether they are locally or more widely applicable, all respectively
Define Matter
Matter is anything with mass and volume
Define Composition
Composition describes what the matter is made up of
Define a “Substance”
Matter with a defined composition
Define a “Mixture”
A substance who’s composition can be physically separated
Define a “Pure Substance”
A substance who’s composition can’t be separated by physical means
Define Homogenous
A mixture that is the same throughout
Define Heterogenous
A mixture that is not the same through out
Define a “Compound”
A pure substance who’s components can be chemically separated
Define an “Element”
A pure substance who’s components can’t be chemically seperated
What are the 4 main points of Dalton’s Atomic Theory?
- All matter is made out of atoms that are indestructible, hard, indivisible spheres
- All atoms of a given mass are identical in mass and property
- Compounds are formed by two or more different kinds of atoms
- Chemical reaction is a rearrangement of atoms
Define “Chemistry”
The study of properties and transformations of matter, and the interaction of matter and energy
Define “Science”
Science is the systematic organization of knowledge in the form of testable explanations and predictions about the universe
Define a “Property”
Something about a substance that can be felt with the 5 senses or measured with an instrument
Define a “Physical property”
A property that can be perceived by our 5 senses or by an extension of our senses (instruments) without any chemical manipulation of the substance
Define a “Chemical property”
Something which can be perceived by our 5 senses or an extension of them (instruments) only after chemical manipulation
Give an example of a physical property
Density etc.
Give an example of a chemical property
Toxicity or acidity etc.
What do physical and chemical properties, together, help us do?
Identify a substance!
What is Energy?
Energy is the ability to do work
What is potential energy?
Potential energy is the ability to do work that comes from position (i.e an item picked up off the ground has potential energy)
What is kinetic energy?
The ability to do work that comes from motion (i.e atoms that constantly bump into each other have kinetic energy)
Define “Heat”
The transfer of kinetic energy from a hotter body, to a cooler body (FYI Heat NEVER transfers from a colder body to a hotter body)
Define “Temperature”
A measure of heat (describes how hot something is relative to a predetermined scale)
How many Kelvins (K) make 1 Degree Celsius (⁰C)?
273.15 K = 1⁰C
Solid ➡️ Liquid ?
Melting (fusion)
Liquid ➡️ Gas ?
Evaporation (boiling/vaporization)
Gas ➡️ Liquid
Condensation
Liquid ➡️ Solid
Freezing
Gas ➡️ Solid
Sublimation
What is the SI Units for mass? Is it a base unit?
kg, yes it’s a base unit
What is the SI unit for temperature? Is it a base unit?
K (Kelvin), yes it’s a base unit
What is the SI unit for density? Is it a base unit?
kg/m^-3, no, it’s a derived unit
Define a “Transformation”
A transformation is the change of one substance into another
Define a “Physical transformation”
A physical transformation is change that does not change the chemical identity of the substance. It’s always reversible
Define a “Chemical transformation”
A chemical transformation changes the chemical identity of the substance; a new substance is produced. It’s sometimes reversible but usually non-reversible
Define “Measurement”
Measurement is using a instrument to quantify a property is a substance relative to an internationally agreed on standard
What do protons and neutrons both approximately weigh? What does an electron approximately weigh?
Protons and neutrons both approximately weigh 1 amu. (1.007,1.009) Electrons approximately weigh 0 amu (0.005)
what does 2 atoms are bonded mean?
It means that there’s a chemical bond between them, an attractive force between the two adjacent atoms
Which has greater electronegativity, ionically bonded atoms (salts), or covalently bonded atoms (molecules)?
The salts have greater electronegativity than the molecules
Describe molecules
Molecules are a small bunch, they have fixed mass and size
Describe salts
Salts are lattices of alternating cation and anions they do not have a fixed mass or size
What is the smallest part of the lattice of salt called?
The unit cell
What is the relationship of mass with protons and nutrons
Mass # = Protons + Nutrons
Define “amu”
1/12th the mass of 1 C-12 atom exactly
Define “mol”
The chemists dozen, exactly 6.022x10^23
What are the general solubility rules?
All salts of the group 1 cations are soluble
All ammonium salts are soluble
All nitrates, perchlorates and acetates are soluble
All halides are soluble except when with Ag+,Hg22+ and Pb2+
