The molecule shown in the figure has two blue spheres.

Slides:

Advertisements

Similar presentations

QUESTION: The symbol 13C or C-13 represents an atom with… A. 13 protons, B. 13 electrons, C. 13 neutrons D. 13 nucleons The atomic number of a carbon atom.

Advertisements

QUESTION: A 25.0 gram sample of a compound is found to be 24% chlorine by mass. What is the percentage of chlorine in a 50.0 g sample of the compound?

How to tell from the formula if a compound is ionic:

A mole of atoms contains exactly 6.02x1023 atoms.

What is the molar mass of Na2SO410H2O?

Mass of proton : x kg, or u QUESTION: Which of the following has the largest total mass? A. 2 protons + 4 electrons B. 2 neutrons.

QUESTION: Which of the following elements is a transition metal? A. silicon, B. lead, C. sodium, D. chromium SCRIPT: Which of the following elements.

How to tell from the name if a compound is ionic:

SO3: one Sulfur atom: 16 protons

Which of these is the formula of a reactant in this reaction?

Smallest set is obtained if greatest common factor is 1

QUESTION: Which of the following describes a cation? A. an aluminum ion (Al3+), B. an oxygen atom that has gained 2 electrons C. an ion with 17 protons.

Ions are formed by loss or gain of electrons.

Consider the combustion of propane: C3H8 + O2  CO2 + H2O (unbalanced)

What is the molar mass of Ca(NO3)2?

HCl and HF ionize in water. HCl(aq)  H+(aq) + Cl-(aq)

Here’s a general strategy for determining empirical formulas.

QUESTION: Consider the following partially-drawn structure of 2-butene (C4H8) where only the C atoms are shown: C-C=C-C When this structure is completed.

QUESTION: Which of the following describes an anion? A. a sodium ion (Na+), B. a calcium ion that has lost 2 electrons C. an ion with 8 protons and 10.

QUESTION: Which of the following is a metalloid? A. Potassium, B. Silicon, C. Iron, D. Helium SCRIPT: Which of the following is a metalloid? A.

Steric number of C in the structure is 3  sp2 hybrid

Mass of proton or neutron: 1.0 u Mass of electron: u

Trends in atomic size: opposite of trend in ionization energy

CLICK Here are some possible molecular formulas When x=1, we have NO2.

QUESTION: Which of the following elements is the best electrical conductor? A. carbon, B. germanium, C. manganese, D. iodine SCRIPT: A. carbon,

Ions are formed by loss or gain of electrons.

Ammonium sulfide is an ionic compound. Cation is ammonium ion. NH4+

QUESTION: Which of the following elements is a metal that belongs to a main group or representative group? A. magnesium, B. zinc, C. sulfur, D.

To construct the ground state electron configuration,

Since both carbon and oxygen are nonmetals, choice C is wrong.

Diatomic = “di” + “atomic” “di” = Greek prefix; means “two”

One Ca2+ ion: +2 One CO32- ion: -2

There are 3 orbitals in a p subshell (ml = -1, 0, or +1).

Ions are formed by loss or gain of electrons.

Here’s a general strategy for determining empirical formulas.

QUESTION: Which type of element has the lowest electronegativity? A. a metal, B. a nonmetal, C. a metalloid Electronegativity is a measure of the.

Mathematically, this implies that the ratio of the amount of element

How many neutrons does an O-18 atom have? A. 8, B. 10, C. 16, D. 18

One Na+ ion: +1 One CO32- ion: -2

Cobalt(II) chloride is an ionic compound. Therefore:

What is the Kelvin temperature equivalent to 50.00oF?

HIGHLIGHT carbon in legend

Resonance structures must have same connectivity.

QUESTION: Assume circles and squares in the figures below represent atoms. According Dalton’s atomic theory, which of the figures below best represents.

The oxygen-to-carbon ratio in that sample is x over 36.0 HIGHLIGHT

Uncertainty is at least +1/10 of smallest interval.

Each calcium ion has a charge of +2,

B. Mg + O2  MgO + O C. Mg2 + O2  2 MgO D. 2 Mg + O2  2 MgO

Choice A is obviously a correct formula --- it has four hydrogen atoms

Allowed values of principal quantum number (n): positive integers

Which figure below best represents an aqueous solution of CaCl2?

Valence electrons: Cl – 7, O – 6, C – 4, N – 5

Oxoanions have names ending in “ate” or “ite”

Therefore, the correct answer is A.

Iron(III) sulfide is an ionic compound. Therefore:

Ions are formed by loss or gain of electrons.

For which pair of molecules does dipole-dipole interaction occur?

CLICK PAUSE END RECORDING

QUESTION: What is the maximum number of of electrons that can be assigned to a 2p orbital of an atom? A. 2, B. 3, C. 6, D. 10 Pauli’s Exclusion.

A. an element and two compounds, B. two elements and a compound,

Here’s a general strategy for determining empirical formulas.

QUESTION: Assume that circles and squares in the figure below represent atoms. According to Dalton’s theory, which of the changes indicated is possible?

Sodium phosphate is an ionic compound. Cation is sodium ion. Na+

QUESTION: Which of the structures below is valid for the HOCl molecule? A. 1, B. 2, C. 3, D v.e. 12 v.e. 10 v.e. SCRIPT: Which of the structures.

What do molecules and polyatomic ions have in common?

We now have a mixture of 3 substances --- the original compound

Potassium hydrogen phosphate is an ionic compound.

represented by a pair of filled circles,

K2CO3 is an ionic compound. Cation is potassium ion: K+

Which of the following is not a balanced chemical equation?

Presentation transcript:

The molecule shown in the figure has two blue spheres. QUESTION: Which of these is not the formula of the compound represented by the figure below, if blue spheres represent carbon atoms, white spheres represent hydrogen atoms and red sphere represents an oxygen atom? A. CHO, B. C2H6O C. C2H5OH, D. CH3CH2OH The formula of a molecular compound reflects the composition of each molecule in the compound. Subscripts indicate how many atoms of each kind are present in the molecule. SCRIPT: Which of these is not the formula of the compound represented by the figure here, if blue spheres represent carbon atoms, white spheres represent hydrogen atoms and red sphere represents an oxygen atom? A. CHO, B. C2H6O C. C2H5OH, D. CH3CH2OH PAUSE CLICK The formula of a molecular compound reflects the composition of each molecule in the compound. Subscripts indicate how many atoms of each kind are present in the molecule. The molecule shown in the figure has two blue spheres. HIGHLIGHT Since, according to the question, blue spheres represent carbon atoms, we should see carbon written in the formula with a subscript of 2, as in choices B and C, HIGHLIGHT C2 in choices B and C or written twice with no subscript, as in choice D. HIGHLIGHT C in CH3 and C in CH2 Remember that a subscript that is not written is implied to be one. Obviously, then, … choice A is NOT a correct formula for the compound represented in the figure. Therefore, the correct answer is A. Let’s look more closely at choices B, C, and D to verify that they are all correct formulas. In the figure, we see six white spheres, HIGHLIGHT as you call out 1…2…3…4…5…6 These represent six hydrogen atoms. Therefore, H should appear in the formula so that the total subscript is 6. In choice B, the subscript of hydrogen is 6. HIGHLIGHT In choice C, hydrogen is written twice and the total subscript is also 6. 5 + 1 equals 6. HIGHLIGHT In choice D, hydrogen is written three times, HIGHLIGHT with subscripts of 3, 2 and 1. …. 3+2+1 equals 6. As far as hydrogen is concerned, we can see that choice A is incorrect. Hydrogen appears in choice A only once, and with no subscript. Finally, the molecule shown in the figure has one red sphere, which represents an oxygen atom. Oxygen appears in all the choices All the choices given have one oxygen with no subscript. The compound represented here is ethanol. It belongs to a class of compounds known as organic compounds. Its formula is, in fact, written more frequently like in choices C and D. The CH3 grouping… HIGHLIGHT CH3 in choice D and CH3 in the figure is quite common among organic compounds. It’s called a methyl group. CALLOUT “methyl” The CH2 grouping… HIGHLIGHT CH2 in choice D and CH2 in the figure. It’s called a methylene group. The CH3CH2 grouping…, HIGHLIGHT CH3CH2 in choice D which is often abbreviated C2H5… HIGHLIGHT C2H5 in choice C is also quite common and is called an ethyl group. The OH group… HIGHLIGHT OH in choices C and D and in figure CALLOUT “hydroxyl” pointing to OH group is also quite common among organic compounds. It’s called a hydroxyl group. Compounds whose molecules have hydroxyl groups are called alcohols. Ethanol is also called ethyl alcohol. CLICK PAUSE END RECORDING

Video ID: 1-24-7 © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08