Atom numbering, writing reaction

STRATEGY Write the nuclear equation for each reaction, representing the daughter nuclide as E, with atomic number Z and mass number A. Then find Z and A from the requirement that both mass number and atomic number are conserved in a nuclear reaction, (a) In a decay, two protons and two neutrons are lost. As a result, the mass number decreases by 4 and the atomic number decreases by 2 (see Fig. 17.7). (b) The loss of one negative charge when an electron is ejected from the nucleus (Fig. 17.8) can be interpreted as the conversion of a neutron into a proton within the nucleus ... 

Conservation of mass and charge are used when writing nuclear reactions. For example, let s consider what happens when uranium-238 undergoes alpha decay. Uranium-238 has 92 protons and 146 neutrons and is symbolized as After it emits an alpha particle, the nucleus now has a mass number of 234 and an atomic number of 90. 

Step 1 Identify the type of decay and write the nuclear reaction, with the mass number and the atomic number of the daughter nucleus written as A and Z, respectively. 

Atoms with identical atomic numbers but different mass numbers are called isotopes, and the nucleus of a specific isotope is called a nuclide. There are 13 known isotopes of carbon, two of which occur commonly (12C and 13C) and one of which (14C) is produced in small amounts in the upper atmosphere by the action of neutrons from cosmic rays on 14N. The remaining 10 carbon isotopes have been produced artificially. Only the two commonly occurring ones are indefinitely stable the other 11 undergo spontaneous nuclear reactions, which change their nuclei. Carbon-14, for example, slowly decomposes to give nitrogen-14 plus an electron, a process we can write as... 

You are given all of the particles involved in an induced transmutation reaction, from which you must write the balanced nuclear equation. Because the alpha particle bombards the aluminum atom, they are reactants and must appear on the reactant side of the reaction arrow. Obtain the atomic number of aluminum and phosphorus from the periodic table. Write out the nuclear reaction, being sure to include the alpha particle (reactant) and the neutron (product). 

On the basis of what you have learned about the physical and chemical properties and reactions of CI2/ Br2, and I2 and/or of HF, HCl, HBr, and HI, write an essay describing clearly what physical and chemical properties and reactions you would expect for elemental astatine (atomic number 85) and/or its acid, HAt (as designated by your instructor). 

The relatively complicated case of CIO + CIO, where two closely related reactive channels (47a) and (47b) are identified, cannot be paralleled for BrO -I- BrO. No stable OBrO molecule (analogous to OCIO) is definitely known, nor has gaseous BrOO ever been detected as a transient or otherwise. Therefore, the dissociation energy of BrOO, if it exists, must be considerably less than the 29kJmol" suggested for CIOO. In the work of Oyne and Cruse, the number of bromine atoms found from reaction of BrO + BrO approached the number of BrO radicals consumed. This result confirms the correctness of writing this reaction as BrO + BrO -> 2Br + O2 and also confirms a lack of stability for the BrOO radical which, by analogy with CIO -I- QO, is likely to be the initial product, with Br, of reaction (49). In this case, the most probable fate of BrOO... 

Boron, atomic number 5, occurs naturally as two isotopes, and B, with natural abundances of 19.9% and 80.1%, respectively, (a) In what ways do the two isotopes differ from each other Does the electronic configuration of differ from that of B (b) Draw the orbital diagram for an atom of B. Which electrons are the valence electrons (c) Indicate three major ways in which the Is electrons in boron differ from its 2s electrons, (d) Elemental boron reacts with fluorine to form BF3, a gas. Write a balanced chemical equation for the reaction of solid boron with fluorine gas. (e) AHf for Bp3(g) is —1135.6 kl/mol Calculate the standard enthalpy change in the reaction of boron with fluorine, (f) When BCI3, also a gas at room temperature, comes into contact with water, the two react to form hydrochloric acid and boric add, H3BO3, a very weak acid in water. Write a balanced net ionic equation for this reaction. 

In the sketch below, the red spheres represent protons and the gray spheres represent neutrons, (a) What are the identities of the four particles involved in the reaction depicted (b) Write the transformation represented below using condensed notation. (c) Based on its atomic number and mass number, do you think the product nucleus is stable or radioactive [Section 21.3]... 

For the most part, when we write reactions such as (2.2) and (2.3), we use the = sign to indicate only that the reaction is balanced, meaning that the same number and kinds of atoms appear on both sides, and that any electrical charges are also the same on both sides. If we want to emphasize that the reaction proceeds strongly or irreversibly we may use an arrow, as in A B, and if we want to emphasize that the two sides are in equiUbrium, we might use A B. However, the = sign includes these possibiUties, and all others. 

The synthesis of the elements with odd atomic numbers has always been a difficult problem for cosmologists to account for. Write a balanced nuclear equation for the following two proposed reactions. 

In each case, the electrons in the atoms are ignored. All of the symbols used to write equations for nuclear reactions represent only the atomic nuclei. Recall that we said we write the symbol for an isotope in the form, where X is the symbol for the element, Z is the element s atomic number (which is determined by the number of protons in atoms of that element), and A is the element s mass number (the sum of the number of protons and neutrons in atoms of that isotope). If we are concerned only with an atom s nucleus, we may also use the term nuclide instead of isotope, since the term isotope commonly refers to the entire atom and includes the atom s electrons. 

Nuclear Reactions LEARNING GOAL Write a balanced nuclear equation showing mass numbers and atomic numbers for radioactive decay. 

Writing and balancing nuclear reactions Just as chemical reactions are written in balanced equations, so are nuclear reactions. Mass numbers and atomic numbers are conserved when writing a... 

Now the product, 2HC1, contains two moles of chlorine atoms. This is just the number of chlorine atoms in one mole of chlorine. The reaction is balanced. We may write... 

When potassium chlorate solution, KClOi, is added to hydrochloric acid, chlorine gas is evolved. Although we can find the half-reaction, 2C1- = Ck(g) + 2e, in Appendix 3, we find no equation with CIQT ion involved. We can surmise that CIO3" is accepting electrons and changing into chlorine. Let us write a partial half-reaction in which we indicate an unknown number of electrons and in which we have conserved only chlorine atoms ... 

H.4 The first box below represents the reactants for a chemical reaction and the second box the products that form if all the reactant molecules shown react. Using the key below write a balanced equation for the reaction using the smallest whole-number coefficients. Assume that if two atoms are touching,... 

Write a balanced chemical equation for (a) the hydrogenation of ethyne (acetylene, C2H2) to ethene (C2H4) by hydrogen (give the oxidation number of the carbon atoms in the reactant and product) (b) the shift reaction (sometimes called the water gas shift reaction, WGSR) (c) the reaction of barium hydride with water. 

There are a number of past and present commercial routes to phenol using benzene as a feed stock. Outline two such processes, writing balanced equations for the reactions involved. Compare the two routes in terms of atom economy. 

In the synthesis of potassium chloride from its elements, metallic potassium is oxidized to form potassium ions, and gaseous chlorine is reduced to form chloride ions. This reaction is shown in Figure 10.10. Each half-reaction can he balanced hy writing the correct formulas for the reactant and product, balancing the numbers of atoms, and then adding the correct number of electrons to balance the charges. For the oxidation half-reaction,... 

Redox reactions do not always take place under neutral conditions. Balancing half-reactions is more complicated for reactions that take place in acidic or basic solutions. When an acid or base is present, or OH ions must also be considered. However, the overall approach is similar. This approach involves writing the correct formulas for the reactants and products, balancing the atoms, and adding the appropriate number of electrons to one side of the half-reaction to balance the charges. 

Typically, reactants and products are represented by their atomic or molecular formulas, but molecular structures or simple names may be used instead. Phases are also often shown (s) for solid, ( ) for liquid, and (g) for gas. Compounds dissolved in water are designated (aq) for aqueous. Lastly, numbers are placed in front of the reactants or products to show the ratio in which they either combine or form. These numbers are called coefficients, and they represent numbers of individual atoms and molecules. For instance, to represent the chemical reaction in which coal (solid carbon) burns in the presence of oxygen to form gaseous carbon dioxide, we write the chemical equation... 

The immediate question is How does one add a single component k from an external reservoir to the crystal according to Eqn. (2.4) without violating any structural constraints, that is, the fixed relations between the numbers of sublattice sites We denote a particular sublattice containing atoms (ions) of component k by x (x = 1,2,..., K) and write the exchange reaction between external reservoir (= buffer P) and crystal sublattice as... 

Since the principle of conservation of masses applies to chemical reactions, coefficients must often be used in writing chemical reactions so that the number of atoms of products is equal to the number of atoms of reactants, An example is the reaction of two moles of hydrogen with one mole of oxygen to form ru n moles of water... 

H2, Cl2, and Br2 are placed in a flask and heated to 1000 K. (a) What molecular species will be present when the reactions come to equilibrium Neglect atomic species. Consult Table 9.1. (b) Write all the equilibrium reactions that are possible for this system. Neglect reactions that are the reverse of reactions already written and reactions differing from the others only by a multiplicative factor. Also ignore reactions that are nonproductive, i.e., ones in which the reactants and products are identical. Choose balanced equations that have the lowest possible, whole-number... 

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