Chapter 1-3 Notes Flashcards
What is Dalton’s Atomic Theory? (5 points)
- All matter is made up of atoms.
- Atoms of the same element are identical in size, mass and properties. Different elements have differently specialized atoms.
- Atoms cannot be divided.
- Chemical compounds are forms when atoms of different elements combine in whole-number ratios.
- Atoms can be combined, separated and rearranged.
What differs between Dalton’s theory and modern theory? (2 points)
- Instead of atoms being identical in size, mass, and other properties, atoms of an element have an average mass that is unique to an element.
- Atoms cannot be subdivided, created, or destroyed in ordinary chemical reactions. But these changes can occur in nuclear reactions.
Who discovered the electron and how?
JJ Thomson, using a cathode ray
What was Thomson’s Atomic Model known as?
The plum pudding model. He believed that electrons were like plums embedded in a positively charged pudding.
Who determined the mass of the electron?
Robert Millikan
Who was Robert Millikan?
He discovered the mass of the electron.
What were the conclusions from the study of the electron? (3 points)
- All elements contain identically charged electrons.
- Atoms are neutral. There must be positive particles in the atom to balance the electrons’ negative charge.
- Electrons have so little mass that other particles account for most of the mass.
What was Rutherford’s Gold Foil Experiment?
Alpha particles are helium nuclei. Particles are fired at a thin sheet of gold foil. Particle hits on the detecting screen are recorded.
What were Rutherford’s findings?
Conclusions from the experiment:
- Most of the particles passed right through
- Few particles were deflected
Conclusions: The nucleus is small, dense, and positively charged.
Describe the structure of an atom.
- Most of the mass is in the nucleus (protons and neutrons).
- Electrons are found outside of the nuclear (the electron cloud).
- Most of the volume of the atom is empty space.
What are quarks?
Quarks are fundamental particles that make up protons and neutrons in the atom’s nucleus. They are held together by gluons.
What is a hadron?
A hadron is a combination of particles that have a net charge.
What gives the identity of an element?
The number of protons
What is the numerator and denominator of the fraction in front of elements?
The numerator is the mass number (protons and neutrons), while the denominator is the number of protons.
How do you write an ionic formula?
- Write the ions and their charges. The anion (negative) follows the cation (positive).
- Criss-cross the charges.
What is Avogadro’s number and why is it important?
6.022*10^23
This relates the number of moles in a pure substance with the number of particles in that sample. (Translation: One mole of whatever will always be Avogadro’s number.)
What determines if something is an acid?
The presence of hydrogen
How do you name an acid NOT containing oxygen?
- The H+ cation becomes the prefix “hydro-.”
- The suffix “-ic” gets added to the root name of the anion.
Example: HBr, hydrobromic acid
How do you name an oxyacid?
If the name of the polyatomic anion ended with “-ate,” it will be changed to “-ic.” Change it to “-ous” if it was “-ite” originally.
H2SO4, sulfuric acid
What is the purpose of mass spectrometry?
Produces spectra of masses from the molecules in a sample of material and fragments of the molecules
What are the uses for mass spectrometry? (5 uses)
This can be used to determine elemental compositions of a sample, masses of particles and molecules, chemical structures of molecules, the identity of unknown compounds (matching to known spectra), and isotopic composition of elements in a molecule.
What are the stages of mass spectrometry? (3 stages)
- The ionizer converts some of the sample into ions.
- Mass analyzers separate the ions according to their mass-to-charge ratio.
- The detector records either the charge induced or the current produced when an ion passes by or hits a surface.
What is a digit that is estimated called?
Uncertain. A measurement always has some degree of uncertainty, because measurements are performed using instruments that don’t have an infinite number of decimal places.
What the difference between accuracy and precision?
Accuracy if the agreement of a particular value with the true value. Precision refers to the degree of agreement among several measurements made in the same manner.
What’s the difference between a random error and a systematic error?
A random error is a measurement that had an equal probability of being high or low from the accurate result. A systematic error occurs in the same direction each time (high or low), usually a result of a flaw in technique. (This results in precise, but not accurate measurements.)
What is the rule of significant figures when multiplying and dividing?
Use the least amount of significant figures as indicated by one of the numbers being multiplied or divided.
What is the rule of significant figures when adding and subtracting?
Use the least amount of decimal places as indicated by one of the numbers being multiplied or divided.
