The true statement regarding the properties of elements in a period on the periodic table are
<u><em>They have different properties that repeat across the next period.</em></u>
Further Explanation:
The periodic properties are characteristics that are associated with the different elements found in the periodic table. The origin of different properties is the difference in the atomic structure of the different elements.
For a systematic study of the chemical and physical properties of different elements, they are placed in certain columns called groups and horizontal rows called periods.
The fundamental basis of this arrangement is periodic law that states that chemical elements must be listed in order of their increasing atomic number. When elements are placed in groups in such order it was observed that elements with similar chemical properties repeated after fixed intervals, this was discovered by the Russian scientist Mendeleev. For example, the elements placed in group 1 that included lithium sodium potassium cesium all reacted vigorously with water. Similarly, the elements in group 17 were termed as halogens as they all readily formed salts with metals of group 1.
Each successive element in a particular horizontal row, however, differs from each other because of addition of electrons in each successive element. When the electrons are added to each successive element in period the effective nuclear charge is increased which essentially increases the force of attraction between the nucleus and the electrons in the valence shell. Consequently, the properties such as ionization enthalpy, electronegativity, atomic radii are also changed.
When the next group is encountered for filling of electrons the electrons are added to the next shell, however, the number of electrons in the valence shell is same as that of the element present in the group above it. This is because the electronic configuration for the outermost shell is similar. This is the reason that elements belonging to same group have similar chemical properties.
Therefore the properties are repeated in the next period as the elements lie in the same group and thus the elements in the same period will repeat their properties across next period.
Learn more:
1. How many moles of Cl are present in 8 moles of 
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2. Determine the moles of water produced: brainly.com/question/1405182
Answer details:
Grade: High School
Subject: Chemistry
Chapter: Periodic classification of elements
Keywords: Periodic properties atomic structure groups, periods, periodic law chemical properties ionization enthalpy, electronegativity, atomic radii, effective nuclear charge, valence shell, electronic configuration.
