chem 260 (exam 1)
mass of products = mass of reactants
-splits into subatomic particles.
such as: electrons (-ve), protons (+ve) and neutrons (neutral)
-concept of splitting atom started with discovery of: cathode rays, x-rays, the electrons.
proposed that cathode rays consist of tiny negatively charged particles, which we now call electrons.
measured the charge: mass ratio of the electron.
mass/charge = -1.76x108 coulombs.
charge on any drop was always a whole number multiple of -1.6022x10-19 coulombs.
further calculated the mass of an electron to be 9.10x10-28 g.
atoms consists of diffused cloud of positive charges and electrons are embedded randomly in it.
3 types of rays produced: alpha (+ve), beta (-ve) and gamma (no charge).
beam of dense, positively charged alpha particles emitting from radium was aimed at thin gold foil.
demonstrated the existence of a positively charged nucleus, a dense central core within the atom.
a few particles were deflected.
occasionally a very few particles were deflected at very large angles.
thus he proposed nuclear atom of the atom.
an atom consists of a tiny massive center of positive charge (the nucleus) surriunded by electrons, which are moving around the nucleus.
determines the chemical identity of an atom.
masses of atomic particles expressed in atomic mass unit (u).
mass of isotope 1 in amu) x (% abundance isotope1/100)
listed the elements in order of their atomic masses and found that elements with similar chemical properties fell in the same column.
proposed table base on observation supported by scanty understanding.
each element is represented by its symbol and atomic mass.
elements can be classified as metals, non-metals, metalloids or semi-metals.
main group elements- A
transition elements or metals- B
-good electrical conductors.
-good heat conductors.
-malliable and ductile
-lose electrons during chemical change.
-poor conductors or non-conductors
-poor heat conductors
-dull in appearance
-gain electrons during chemical change.
diatomic polyatomic polyatomic monoatomic
diatomic: H2 , N2 , F2, HCl and CO
polyatomic: H2 O, NH3, CH4,
monatomic: Na+, S2-
polyatomic: OH-, NH4
formed when an atom looses one or more electrons.
formed when an atom gains one or more electrons.
amount of any substance that contains the same no. of entities (atoms, molecules or ions) as there are in exactly 12g of carbon-12 isotopes.
1 mole of atoms=6.022x1023 atoms=avogadro's no. (NA)
O, Na, Cl, F
diatomic molecules : H2, O2
polyatomic: P4, S8
basic unit=formula units
NaCl, KBr, CaCl2
shows the no. of atoms of each kind in one molecule of the compound.
-help understand natural world.
-framework for organizing scientific knowledge.
-any non-zero digit is significant. eg. 1.52g (3 sig. fig.)
-zeroes between non-zero digits are always significant. eg. 1.08km (3 sig. fig.)
-leading zeroes. eg. 0.0045kg (2 sig. fig.)
-trailing zeroes. eg. 4.000g (4 sig. fig.)
-no. in a room
kg/g3 or g/cm3 (density)
eg. burning of gas or oil or wood.
-dissolving a penny in nitric acid.
eg. boiling and freezing water.
-dissolving sugar in water.
-condensation of moisture on a cold surface.
-a guess that can be tested by experiment.
-central to our understanding of diverse disciplines in science and engineering.
-consists of atoms and molecules (the particulate level)
-anything in universe that has mass and takes up space.
Words From Our Students
"StudyBlue is great for studying. I love the study guides, flashcards, and quizzes. So extremely helpful for all of my classes!"
Alice, Arizona State University
"I'm a student using StudyBlue, and I can 100% say that it helps me so much. Study materials for almost every subject in school are available in StudyBlue. It is so helpful for my education!"
Tim, University of Florida
"StudyBlue provides way more features than other studying apps, and thus allows me to learn very quickly! I actually feel much more comfortable taking my exams after I study with this app. It's amazing!"
Jennifer, Rutgers University
"I love flashcards but carrying around physical flashcards is cumbersome and simply outdated. StudyBlue is exactly what I was looking for!"