32 terms

GES 105 - Chemistry Midterm

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What is an element
Any material that is made up of only one type of atom
How many elements are on the periodic table
more than 100 elements.
What is the most abundant element in the universe
hydrogen
What is the origin of the elements
the stars
What is known about atoms
perpetually moving
tinier than the wavelengths of visible light
recycling among innumerable forms
mostly empty space
Atoms are made of
positively charged protons
electrically neutral neutrons
negatively charged electrons
What is CO2
carbon dioxide.
One atom of Carbon, two atoms of Oxygen.
The symbol Co is the element colbalt (atomic form).
What does the atomic number of an element match
the number of protons in the nucleus of an atom
What group are Noble or inert gases in
group 18 (8A) of the periodic table
How many do they have in their valance shells
Those atoms all have filled valence shells so they are unreactive. He (2 valence electrons), all the rest have 8 valence electrons (octet).
Where do the radioactive decay of natures elements occur
all around us
Alpha Radiation
Helium nucleus with +2 charge, most ionizing, least penetrating
Beta radiation
high speed electron, negative charge, moderate penetrability
Gamma radiation
non-ionizing, no mass, highest penetrability
What is Radon at standard temperature and pressure
gas
Is food safe to eat when exposed to gamma radiation?
yes, the food is safe to eat
How much of the isotope is remaining after 4 days if it has a half life of one day
one-sixteenth
How much does the mass number of the resulting element reduce by when it ejects an alpha particle
the mass number of the resulting element reduces by 4
Does attraction between molecules go up or down as temperature goes down?
Attractions between molecules goes up as temperature goes down
Where is there more attraction? Less attraction?
Maximum attraction is found in solids and gradually less attraction is found in liquids, then in gasses.
Physical change
A change of state of matter
ex: Solid to liquid
Chemical Change
Atoms in the reactant molecules break apart and form new molecules.
Compound
different atoms bonded together
Mixture
more than one kind of atom and molecule.
How can you tell how many bonds an element can make
the number of valance electrons
Ionic bonds
form between metals and non-metals
covalent bonds
form between non-metals (including the halogens)
metallic bonds
bonds formed between metals
Polar bonds
exist between two atoms that have a large electronegativity difference between them.
ex: O-H is the most polar bond, like the ones in H2O.
what tells you how many valance electrons an element has
the group number
group
columns
period
rows