The half-life of Th-232 is 1.405 × 10¹⁰ years
Time elapsed = 2.8 x 10⁹ years
Equation of radioactive decay:
A = A₀ = (1/2)^ t/t₁/₂
where A₀ is the initial amount, A is the amount after time t, t₁/₂ is the half file
The fraction of thorium-232 that remains in the rock after 2.8 billions years is,
A/A₀ = (1/2) ^ (2.8 x 10⁹/ 1.405 × 10¹⁰) = 0.871
Therefore, the percentage of thorium-232 in the rock that was dated at 2.8 billions year = 87.1%
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Yes they do. But a very small kinetic energy. They vibrate in fixed positions
Answer:
1. Core electrons = 1s²; Valence electrons = 2s² and 2p³
2. Core electrons = 1s², 2s²,m2p⁶; Valence electrons = 3s² and 3p⁵
Explanation:
The electrons in an atom of an element are generally divided into two groups: the core electrons and the Valence electrons
Valence electrons are those electrons which are located of or found in the outermost shell or highest energy level of an atom. These valence electrons are the one that determine the chemical reactivity of an atom as they can participate in bond formation between atoms of the same element or with atoms of other elements. The valence electrons also, generally determine the group to which an element will belong to.
Core electrons on the other hand, are those electrons which are found within the innermost shell or lowest energy levels of the atom. They are strongly attracted to the nucleus of atom and do not take part in chemical bonding. However, they play the important role of shieldingnthe valence electrons from the positive charge of the nucleus thereby assisting the valence electrons in bond formation.
The alkali metals make up Group 1 of the periodic table. This family consists of the elements lithium, sodium, potassium, rubidium, cesium, and francium (Li, Na, K, Rb, Cs, and Fr, respectively). Group one elements share common characteristics. They are all soft, silver metals. Due to their low ionization energy, these metals have low melting points and are highly reactive. The reactivity of this family increases as you move down the table. Alkali metals are noted for how vigorously they react with water. Due to this, they are often stored in mineral oil and are not found in their elemental forms in nature. These characteristics can be explained by examining the electronic structure of each element in this group. Alkali metals have one valence electron. They readily give up this electron to assume the noble gas configuration as a cation. This makes the elements in this group highly reactive.hope this helps you ok.
