The isotope of an unknown element, X , hass a mass number of...

The isotope of an unknown element, $X$ , hass a mass number of $79 .$ The most stable ion of the isotope has 36 electrons and forms a binary compound with sodium, having a formula of $\mathrm{Na}_{2} \mathrm{X}$ . Which of the following statements is (are) true? For the false statements, correct them. a. The binary compound formed between X and fluorine will be a covalent compound. b. The isotope of X contains 38 protons. c. The isotope of X contains 41 neutrons. d. The identity of X is strontium, Sr.

The isotope of an unknown element, $X$ , hass a mass number of $79 .$ The most stable ion of the isotope has 36 electrons and forms a binary compound with sodium, having a formula of $\mathrm{Na}_{2} \mathrm{X}$ . Which of the following statements is (are) true? For the false statements, correct them.
a. The binary compound formed between X and fluorine will be a covalent compound.
b. The isotope of X contains 38 protons.
c. The isotope of X contains 41 neutrons.
d. The identity of X is strontium, Sr.

Key Concepts

Periodic Table and Element Identification

The periodic table organizes elements by atomic number and recurring chemical properties. By determining the number of protons (atomic number) in an ion and using other clues like the mass number or common ionic charges, one can identify the element. This concept is fundamental in problems that involve correcting or verifying statements about elemental identity.

Chemical Bonding: Ionic versus Covalent

The distinction between ionic and covalent bonding is determined by the nature of the elements involved and differences in their electronegativities. Elements that typically form anions (nonmetals) tend to form covalent bonds with other nonmetals, while reactions between metals and nonmetals usually result in ionic compounds. Understanding the type of bonding helps predict the properties and reactivity of the compounds formed.

Oxidation States and Charge Balance in Ionic Compounds

This concept deals with how ionic compounds are composed of cations and anions whose charges balance to give a neutral compound. When a binary compound is formed, knowing the formula and the typical charges helps in deducing the oxidation state of the element involved. For example, if a compound with sodium (which typically forms a +1 ion) has the formula Na?X, then element X must have a charge of –2, guiding its identification.

Ion Formation and Electron Configuration

Understanding how ions are formed is key when evaluating electron counts. The number of electrons in a stable ion can differ from that in the neutral atom, and this difference is determined by the gain or loss of electrons to achieve a stable, often noble gas, configuration. Recognizing the relationship between the proton count and electron count in ions is essential for determining the element’s identity or its chemical behavior.

Isotope Notation

Isotope notation involves the mass number, which is the sum of protons and neutrons in the nucleus. This concept is crucial because it allows one to determine the number of neutrons once the number of protons (the atomic number) is known, and vice versa. In problems like this, using the mass number together with information about electron count or ion charge helps deduce the identity or properties of the element.

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