4: periodic table
molecular (covalent) compounds _______ electrons while ionic compounds ______ electrons
options: transfer or share
share, transfer
(bonus: what two kinds of atoms are molecular/ covalent bonds formed between?)
In a polar covalent bond are electrons equally or unequally shared?
Isotopes have same numbers of _____ and different numbers _____.
protons, neutrons
Write the symbol and name of the ion Sr forms.
(hint: how many electrons does Sr lose or gain to get an octet?)
Sr2+
Strontium ion
Draw the lewis structure for OF2. Name it. Is it ionic or molecular?
draw on board
Does electronegativity decrease or increase as you go from Mg to Ba?
decrease
What is the symbol of the element with the least metallic character in group 4?
C
What is the symbol for the ion with 26 neutrons, 26 protons and 23 electrons? What is its mass number?
Fe3+
mass number: 52 (p+n)
Write the formula and name for compound formed with the silicon and oxygen
SiO2
(ionic or molecular?)
Draw the Lewis structure and predict the molecular shape of SI2
Draw on board
bent (109 °)
(name it!)
For the bond C—O, indicate the partially positive end with δ+ and partially negative end with δ–.
Then, draw the arrow to show the dipole.
(hint: use the electronegativity values)
draw on board
C is δ+ and O is δ–
fill in the blanks:
atom/ion formula: _______
no. of protons: 8
no. of electrons:_______
no. of electrons gained: 2
O2-, 10
What is the electron arrangement of potassium?
2, 8, 8, 1
which of the following pairs of elements would likely form an ionic compound
(a) lithium and chlorine
(b) oxygen and bromine
(c) potassium and oxygen
(d) sodium and neon
(e) cesium and magnesium
(f) nitrogen and iodine
a and c
name it!
(ionic is between a cation and anion only - charged molecules (ions). So it would generally be between metals (NOT metalloids) and nonmetals.
Name and draw the electron dot formula of BCl3
Boron trichloride (draw on board)
What rule does this not follow?
Is the molecule CF4 polar or non-polar?
(hint: draw the structure)
non-polar, draw on board
(Name it!)
What is the group number of representative element X in the ionic compound: Al2X3
(hint: identify the charge on cation)
Group 6
What is the respective group number, period, and group name (if any) of Si and I?
Then, identify each of them as metal, non-metal, or metalloid.
Si (Silicon): Group 4, Period 3, metalloid
I (Iodine): Group 7, Period 5, Halogen, non-metal
Name the ionic compound Mn2O3
manganese (III) oxide
Predict the molecular shape and polarity of PF3
trigonal pyramidal, polar
dipole-dipole attractions
Going down Group 6 (increase/ decrease/ remains the same)
--> the atomic size _______
--> the ionization energy ______
--> the metallic character ______
--> the no. of valence e- _______
atomic size: increases
ionization energy: decreases
metallic character: increases
# valence e-: remains the same
Silicon has 3 naturally occurring isotopes with their mass and abundances given-
Si-28 (27.977 amu): 92.23%
Si-29 (28.9976 amu): 4.68%
Si-30 (29.974 amu): 3.09%
Calculate the atomic mass of Silicon using the weighted average mass method.
28.09 amu
(extra: how do you tell which is the most prevalent isotope without the abundance)
chromium (II) nitrate
What is the molecular shape of SiCl4?
(hint- draw out the lewis structure)
tetrahedral
(is it a polar or non-polar compound?_
What is the major type of attractive forces between particles in the following compounds?
options: dispersion forces, dipole-dipole attractions or hydrogen bonds, ionic bond
1) NF3
2) H2O
3) CF4
4) NaCl
1) dipole-dipole
2) Hydrogen bond
3) dispersion forces
4) Ionic bonds
(which of those 3 intermolecular forces are the strongest? Weakest?)