Atoms, Elements And The Building Blocks Of Matter Flashcards
What are the 3 most important things on a periodic table block?
1) symbol
2) atomic number
3) molar mass
What is the atomic number
The same number as the number of protons in the nucleus of an element, it is also the same number of electrons surrounding the nucleus of an element when its neutrally charged.
How do you find the number of protons or electrons of an element on a periodic table?
Atomic number
Which unit is used to measure atomic mass?
Atomic mass units
What does the atomic mass represent?
The total mass of an atom.
Define the molar mass of an element
The average mass for a mole of substance.
What are the horizontal lines on a periodic table called?
Periods
What are the vertical lines on a periodic table called?
Groups
Label the names of groups on a periodic table
How is the identity of an atom determined?
By the number of protons contained in it’s nucleus.
What are isotopes?
Atoms of an element with different numbers of neutrons.
How is the molar mass calculated?
The molar mass given on a periodic table is the average of the mass of all known isotopes weighted by their percent abundance
Which technique can determine the mass of various Isotopes of an element?
Mass spectrometry
Coefficients in chemical reactions tell you about the reactants & product in terms of?
Moles.
What does avogadro’s number describe?
How many atoms are in a single mole of any given element.
What is Avogadro’s number?
6.022x10^23
Formula of moles
Moles = (particles/6.022x10^23)
What can atomic mass signify?
How many grams are present in one mole of an element
Which equation helps convert grams and moles?
Moles=grams/molar mass
How do you calculate the number of moles of a gas?
Using the ideal gas equation.
PV=nRT
(n stands for moles of gas)
How do you calculate the number of moles of a gas?
Moles = PV/RT P= pressure (atm) V= volume (L) T= temperature (K) R= the gas constant, 0.0821L*atm/mol*K
What is the standard temperature pressure?
P= 1 atmosphere
T= 273 K
One mole of gas always occupies 22.4 L at stp
How do you solve an equation with stp
Moles= L/(22.4L/mol)
At stp how many liters does one mole of gas occupy?
22.4 L
Define molarity:
Expresses the concentration of a solution in terms of volume
How do you know if an equation is talking about molarity?
When you see a chemical symbol in brackets, like [Na^+] is the same as the concentration of molarity of sodium ions
Formula to calculate molarity
M= moles of solute/ liters of solution
What is percent composition?
The percent by mass of each element that makes up a compound
How do you calculate molar mass?
Dividing the mass of each element or compound in a compound by the total molar mass for the substance.
Calculate percent composition in each element of Ca(NO3)2
