General Chemistry Chapter 2
What is the mass number of a chromium atom with 28 neutrons?
28 neutrons + 24 protons = 52
the understood sig fig amount for periodic table masses is?
4 sig figs
Group 2A: Alkaline Earth Metals
6 of them, Be, Mg, Ca, Sr, Ba, Ra all of these metals form ions with a +2 charge in compounds
Group 1A: Alkali Metals
6 of them, Li, Na, K, Rb, Cs, Fr, (not hydrogen) alkali metals form ions with a +1 charge in compounds
avagodros #
6.022x10^23 1 mole of atoms = 6.022 x10^23 atoms
How many neutrons are in atom of nickel with a mass number of 60?
60 - 28 protons = 32 nuetrons
Copper has two naturally occurring isotopes. A typical sample consists of 69.17% (62.939598 amu) and 30.83% (64.927793 amu). Calculate the atomic mass of copper. a) 62.93 amu b) 62.33 amu c) 62.45 amu d) 63.55 amu e) 63.93 amu
d
How many neutrons are in copper-63? a) 18 b) 24 c) 29 d) 34 e) 63
d
how to know which isotope is more abundant than another ?
mass # needs to be closest to the one on the periodic table
share characteristics of both metals and nonmetals
metalloids
1 mole copper atoms = 63.55 g of copper atoms OR 1 mol Cu = 63.55 g This quantity is also known as the
molar mass (an older term is atomic weight) Molar mass = MM = 63.55 g / mole (for copper)
do not conduct heat and electricity not ductile or malleable
nonmetals
nucleus( the tiny heart of the atom) is composed of ____________________ and _________, each having a mass of around 1 amu. The nucleus is surrounded by ___________ which have negligible mass, but do have an electrical charge of -1
protons (+1) and neutrons electrons
groups on the periodic table are
the vertical columns of elements they have similar chemical and physical properties
protons and electrons =
atomic number; ex Na atomic number 11 so there are 11 protons/electrons
1) From the results of his gold foil experiment, Ernest Rutherford concluded that a) electrons have a charge of +1.602 ´10-19C. b) atoms contain exactly equal numbers of neutrons and protons. c) atoms are composed of a small, dense nucleus surrounded by a cloud of electrons.
atoms are composed of a small, dense nucleus surrounded by a cloud of electrons
Law of Conservation of Matter
atoms are not created or destroyed during a reaction, only rearranged total mass of reactants = total mass of products
Group 3A most important thing
+3 charge
group 5A group 6A 7A
-3 -2 -1
1 amu =
1 amu = 1.661 x 10-24g.
2 statements to describe a mole ?
1) a counting unit like a dozen 2) 1 mole of particles is equal to 6.022x10^23 particles
Use the molar mass (MM) to convert from:
1) mass to moles 2) moles to mass
Use Avogadro's number (NA) to convert from:
1) number of atoms to moles 2) moles to number of atoms
allotrope
Different forms of the same element like graphite and diamond
an alternate name for the periodic chart, which is?
The Gram-Mole Chart The name is justified because underneath the symbol for each element is the number of grams that one mole of atoms of the element weighs. For example, one mole of copper atoms has a mass of 63.55 grams
All of the following statements are true EXCEPT a) for any neutral element, the number of protons and electrons are equal. b) isotopes of an element have the same atomic number. c) the mass number is the sum of the number of protons and neutrons. d) the atomic number equals the number of protons. all atoms of a given element have the same mass number.
a) all atoms of a given element have the same mass number.
Which of the following atoms contains the largest number of neutrons? a)31,15 P b)28,14 Si c)32,16 S d)36,16 S e)35,17 Cl
d)36,16 S
periods on the periodic table are
each horizontal row of elements
Protons Electrons Neutrons what is their electric charge and mass?
electrical charge Mass (amu) Positive (+1) 1.007 negative (-1) 0.0005 no electrical charge 1.009
element equals which letter mass number equals which letter
element (Z) mass #(A)
. Isotopes are types of atoms of the same _________but different _________
element (same Z) mass number (A)
law of chemical periodicity
element properties are periodic functions of their atomic numbers
The measurement unit for molar mass is
g/mol
We can also refer to the types of atoms in an element as ___________ of that element.
isotopes
to find neutrons you do what?
mass # - atomic number