ATOMIC THEORY Flashcards
a. 4.3 x 10E4 + 2.9 x 10E5 =
b. 6.8 x 10E-6 + 5.2 x 10E-5 =
c. (5.7 x 10E8) (3.2 x 10E-6) =
d. (7.9 x 10E-6) / (4.3 x 10E7) =
divide the number and then exponent round sig figs
4.6x10E6
5.9x10E-5
1.8x10E3
1.8x10E-13
What is the mass of a piece of metal that has a density of 7.50 g/cm3 and a volume of 25.89 cm3?
D=M/V 194 g round to sig figs of least accurate
Dalton, what did he do regarding atomic theory? What were his Postulates (in order)?
Dalton gave 4 postulates
all matter is composed of atoms
atoms of the same element are identical
Different elements have different atoms
atoms combine in simple whole-number ratios to form compounds
J.J. Thompson, what did he do regarding atomic theory?
discovered the electron
found charge/mass ratio e-/mass ratio = -1.76x10E8 c/g
Rutherford, what did he do regarding atomic theory?
found most of the atom is empty space with electrons scattered throughout
nearly all mass and positive charge are located in the nucleus
Milikan, what did he do regarding atomic theory?
found the charge of an electron and helped JJ Thompson calculate the mass of an electron -1.6x10E-19
Daltons Postulates in order.
all matter is composed of atoms
atoms of the same element are identical
Different elements have different atoms
atoms combine in simple whole-number ratios to form compounds
What is the average atomic mass of an element with the following isotopes?
Mass % Composition
23.9 10.0
24.3 20.0
23.3 60.0
23.1 10.0
23.6 amu add all and round to least accurate collumn
What is an Atom?
The smallest unit
Electrically neutral
p+ = e- = Atomic# (Z)
The number of protons in the nucleus is given by the
Atomic Number (Z)
The mass of an atom is found by adding the number
of protons and the number of neutrons (n0)
A = atomic Mass
A = Z + n0 Z = A - n0 n0 = A - Z
What is an Ion?
An atom that has lost or gained electrons
Is NOT electrically neutral
The charge can be positive or negative
The charge must be shown as a part of the
symbol of the ion
It CAN NOT be called an atom
Explain the difference between an atom, an Ion, and an Isotope of lithium.
An atom of lithium is electrically neutral and has the same protons and electrons
An ion of lithium has a +1 charge as lithium will lose 1 electron and become Li+
An isotope of Lithium is electrically neutral but has a different number of neutrons
Give the electron configuration for Magnesium (Mg). Use kernel method
Mg: [Ne]3s2
Give the electron configuration of Potassium (K). Use longhand method.
K:1s22s22p63s23p64s1
What is an Isotope?
Most elements are composed of a group of atoms
with the same number of protons but with different
numbers of neutrons
Together the group is referred to as the Isotopes of
the element
Isotopes will have different masses due to the
difference in neutrons
1p+ = 1.7x10 -27 g = 1 amu (Atomic Mass Unit)
1 n0 = 1.7x10 -27 g = 1 amu
The periodic table only reports one mass value per
element. This is the element’s Average Atomic Mass(m)
Give the names and symbols for two metallic ions and two non-metallic ions that have the same electron configuration as neon.
Neon configuration :1s22s22p6
elements with same config:
Al+3,Mg+2,Na+1 -> metallic ions
F-,O-2,N-3 -> non metallic ions
