Answer:
About 60.
Explanation:
Mendeleev knew of 63 elements. He wrote their properties on cards and arranged them in order of atomic mass.
That's how he discovered that the properties of elements are periodic functions of their atomic masses.
Answer:
Explanation:
Temperature measures the average kinetic (or motion) energy of the particles within a substance.
Answer:
The correct answer is 2.75 grams of HCl.
Explanation:
The given balanced equation is:
CaCO₃ (s) + 2HCl (aq) ⇒ CaCl₂ (aq) + H₂O (l) + CO₂ (g)
Based on the given information, one mole of calcium carbonate is reacting with two moles of HCl. The molecular mass of HCl is 36.5 grams, thus, the mass of 2 moles of HCl will be, 36.5 × 2 = 73 grams
The molecular mass of CaCO₃ is 100 gram per mole, that is, the mass of 1 mole of CaCO₃ is 100 grams, therefore, the mass of HCl required for reacting with 3.75 grams of CaCO₃ will be,
= 3.75 × 2 × 36.5 / 100 = 2.74 grams of HCl.
Personal experience from Ag Mech classes-Concrete cools faster than metal.
Answer: The Lattice energy is the energy required to separate an ionic solid into its component gaseous ions <em>or</em>
It is the energy released when gaseous ions combine to form an ionic solid.
Explanation:
The lattice energy depends on the ionization energies and electron affinities of atoms involved in the formation of the compound. The ionization energies and electron affinities also depends on the ionic radius and charges of the ions involved. As the ionic radius for cations <em>increases</em> down the groups, ionization energy <em>decreases</em>, whereas, as ionic radii <em>decreases</em> across the periods , ionization energy <em>increases</em>. The trend observed for anions is that as ionic radii <em>increase </em>down the groups, electron affinity <em>decreases. </em>Across the period, as ionic radii <em>increases</em> electron affinity <em>increases</em>. Also, as the charge on the ion <em>increases,</em> it leads to an <em>increase</em> in energy requirement/content.
Therefore, for compounds formed from cations and anions in the same period, the highest charged cation and anion will have the highest lattice energy. For example, among the following compounds: Al2O3 (aluminium oxide), AlCl3 (aluminium chloride), MgO, MgCl2 (magnesium chloride), NaCl, Na2O (sodium oxide); Al2O3(aluminium oxide) will have the highest lattice energy, thus will be hardest to break apart because its ions have the highest charge.
