Atomic Theory
This ancient Greek philosopher first proposed that matter was made of indivisible particles called "atomos."
Who is Democritus?
According to Dalton, this is what all matter is composed of.
What are atoms?
This subatomic particle has a positive charge and is located in the nucleus.
What is a proton?
This is the term for numbers written in the everyday format, like 5,400,000.
What is standard notation?
This is the rule regarding zeros that fall between two nonzero digits (like the 0 in 405).
What is they are always significant?
This is the meaning of the Greek word "atomos," which Democritus used to name his particles.
What is "indivisible" (uncuttable)?
According to Dalton, atoms of a given element are all this, in size, mass, and properties.
What is identical (the same)?
This subatomic particle has no charge (neutral) and is located in the nucleus.
What is a neutron?
This is the general form of a number written in scientific notation. (How do we format scientific notation?)
What is a coefficient (between 1 and 9) multiplied by 10 raised to a power (exponent)?
This is the rule for leading zeros (zeros before the first nonzero digit, like in 0.0056).
What is they are never significant?
Unlike Dalton, this is how Democritus arrived at his ideas about atoms using this method rather than experimentation.
What is philosophical reasoning/thought (not experimentation)?
According to Dalton, atoms of different elements differ in these two properties.
What are size and mass (and properties)?
This subatomic particle has a negative charge and is found outside the nucleus, in the electron cloud/energy levels.
What is an electron?
Write 0.00042 in scientific notation.
What is 4.2 × 10⁻⁴?
This is the rule for trailing zeros in a number WITH a decimal point (like 5.00).
What is they are significant?
This scientist developed the first modern, experimentally-based atomic theory in the early 1800s.
Who is John Dalton?
According to Dalton, this is what happens to atoms during a chemical reaction. They cannot be created, destroyed, or divided, only this.
What is rearranged/combined (in whole-number ratios)? (Law of Conservation of Mass)
This subatomic particle has the smallest mass, roughly 1/1836 the mass of a proton.
What is an electron?
How many times and what is the direction that the decimal point has to move in the following notation: 6.02 × 10²³
What is moving the decimal point 23 places to the right?
This is the number of significant figures in the measurement 0.00230.
What is three?
This is the key difference between Democritus's and Dalton's approaches to describing atoms.
What is Dalton used scientific experimentation and evidence, while Democritus used only philosophical speculation?
This part of Dalton's atomic theory was later proven incorrect by the discovery of subatomic particles.
What is the idea that atoms are indivisible?
These two subatomic particles have approximately equal mass to one another.
What are protons and neutrons?
What should an exponent be when converting a number LESS than 1 into scientific notation.
What is negative?
When multiplying or dividing measurements, this is the rule for determining sig figs in your final answer.
What is the answer should have the same number of sig figs as the measurement with the fewest sig figs?