The Atomic Number and Atomic Mass of ²⁸Si₁₄ are 14 and 28 respectively.
Atomic Number:
Atomic Number of Element is the Number of Protons contained by the Element. So, there are 14 Protons in ²⁸Si₁₄.
Atomic Mass:
Atomic Mass of Element is the total number of Protons and Neutrons present in the Nucleus of that element.
So,
Atomic Mass = # of Protons + # of Neutrons
As the Atomic mass of ²⁸Si₁₄ is 28 and it has 14 protons, So # of Neutrons are calculated as,
# of Neutrons = Atomic Mass - # of Protons
# of Neutrons = 28 - 14
# of Neutrons = 14
Result:
In ²⁸Si₁₄ Number of Neutrons are 14, Number of Protons are 14.
Z = 14 , n = 14
Atoms of elements that are nonmetals tend to gain electrons and atoms of metallic elements tend to lose electrons. Metals have few electrons in their valence shells.
By losing those electrons, these metals achieve noble gas configuration and satisfy the octet rule.
Nonmetals that have close to 8 electrons in their valence shells readily accept electrons to achieve noble gas configuration.
An example is the reaction between calcium and oxygen. Calcium is a metal and has 2 valence electrons. Oxygen is a nonmetal and has 6 valence electrons.
Calcium gives up its two valence electrons and oxygen accepts them and an ionic bond is established resulting in the formation of anew compound namely calcium oxide.
Answer:
2.9 grams.
Explanation:
- From the balanced reaction:
<em>Mg + 1/2O₂ → MgO,</em>
1.0 mole of Mg reacts with 0.5 mole of oxygen to produce 1.0 mole of MgO.
- We need to calculate the no. of moles of (1.8 g) of Mg and (6.0 g) of oxygen:
no. of moles of Mg = mass/molar mass = (1.8 g)/(24.3 g/mol) = 0.074 mol.
no. of moles of O₂ = mass/molar mass = (6.0 g)/(16.0 g/mol) = 0.375 mol.
<em>So. 0.074 mol of Mg reacts completely with (0.074/2 = 0.037 mol) of O₂ which be in excess.</em>
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<em><u>Using cross multiplication:</u></em>
1.0 mole of Mg produce → 1.0 mol of MgO.
∴ 0.074 mol of Mg produce → 0.074 mol of MgO.
<em>∴ The amount of MgO produced = no. of moles x molar mass </em>= (0.074 mol)(40.3 g/mol) = <em>2.98 g.</em>
So the first one is yellow and the other one is white
C. 28 KJ
AMU of H2O2 = 2(1) + 2(16) = 34 g/mol
10 g / 34 g/mol = 0.294 mol H2O2
0.294 mol / H = 2 mol / 190 KJ
H = 28.9 KJ
