Dmitry Mendeleev is credited with creating the first periodic table that gained widespread scientific acceptance. He arranged elements by atomic mass and famously left gaps for undiscovered elements, correctly predicting their properties based on the periodic trends he observed.
3662
What is the definition of the term 'periodicity' in chemistry?
Periodicity refers to the recurring trends in the physical and chemical properties of elements as they are arranged in the periodic table. These properties repeat at regular intervals because the electronic configurations of the elements repeat in a predictable pattern as the atomic number increases.
3663
According to the IUPAC standards, what are the total numbers of groups and periods in the modern periodic table?
The modern periodic table, organized by the International Union of Pure and Applied Chemistry (IUPAC), consists of 18 vertical columns known as groups and 7 horizontal rows known as periods. This structure reflects the arrangement of elements based on their atomic number and electronic configuration.
3664
Which block of the modern periodic table encompasses the first and second groups?
The s-block consists of the first two groups of the periodic table, which include the alkali metals (Group 1) and alkaline earth metals (Group 2). These elements have their valence electrons in an s-orbital.
3665
The modern periodic table is organized based on which of the following principles?
The modern periodic table is arranged in increasing order of atomic number (the number of protons in the nucleus). This arrangement resolves discrepancies found in earlier tables based on atomic mass, as it reflects the electronic configuration of elements, which dictates their chemical behavior.
3666
Which two periods in the modern periodic table contain exactly 8 elements each?
Period 2 contains 8 elements (Lithium to Neon) and Period 3 also contains 8 elements (Sodium to Argon). These are known as short periods in the periodic table.
3667
Evaluate the following statements regarding the periods of the modern periodic table: 1. The fourth and fifth periods each contain 18 elements. 2. The seventh period is currently considered incomplete with 33 elements. 3. The sixth period contains 32 elements. Which of these statements are correct?
The fourth and fifth periods contain 18 elements each. The sixth period contains 32 elements, including the lanthanide series. The seventh period is now considered complete with 32 elements following the discovery and naming of elements up to Oganesson (118). Statement 2 is considered outdated, making D the correct choice based on standard textbook definitions.
3668
According to Mendeleev's original periodic law, the physical and chemical properties of elements are periodic functions of which property?
Dmitri Mendeleev formulated his periodic law based on the observation that when elements are arranged in order of increasing atomic mass, their properties repeat at regular intervals. This was the foundational principle before the discovery of atomic numbers.
3669
How many elements are contained within the fifth period of the Modern Periodic Table?
The fifth period of the modern periodic table begins with Rubidium (Z=37) and ends with Xenon (Z=54). This period involves the filling of the 5s, 4d, and 5p orbitals. The total number of elements in this period is 18, which corresponds to the capacity of these subshells (2 + 10 + 6 = 18).
3670
Which electron shells are occupied by elements located in the third period of the periodic table?
The period number corresponds to the principal quantum number (n) of the outermost shell. Elements in the third period have their valence electrons in the third shell, which corresponds to the M shell (n=3), meaning K (n=1) and L (n=2) shells are also filled.
