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According to the kinetic molecular theory for an ideal gas, all gas particles "<span>have collisions that decrease the total energy of the system" but this is not always the case. </span>
<span>Water is known as a polar molecule because the oxygen atom has a greater attraction for electrons than the hydrogen atom does. Oxygen is more electronegative than that of hydrogen creating a partial charges with the hydrogen and oxygen atoms. Also, the electrons of the covalent bond are not shared equally between the hydrogen and oxygen atoms making it polar.</span>
<span>The behavior, or reactivity, of elements in a group, or family will behave similarly because they have the same numbers of valence electrons. An example might be the alkali metals (with the exception of hydrogen, H, which is a gas) which form +1 ions in their compounds, have a relatively low melting point, and react violently with water. Other groups of atoms also show similar properties although different from the alkali metals. This type of behavior is one of the things that helps us categorize the elements into the periodic table of the elements. Mendeleev noticed similarities in the behavior of certain elements that originally allowed him to place them into families and develop that periodic chart</span>
Answer:
alkali metals- Group 1
Explanation:
they have less valence electrons and therefore are more reactive
