Predict a simple reaction from the outer electrons
Grade 10 Science Worksheet - Challenge Me
Circle the best answer, or write your answer on the line.
Ari reacts 8 aluminum atoms (group 13) with oxygen gas (group 16). Electrons lost must equal electrons gained. How many O₂ molecules are used?
Bo reacts 12 magnesium atoms (group 2) with nitrogen gas (group 15). Electrons lost must equal electrons gained. How many N₂ molecules are used?
Esme reacts 12 lithium atoms (group 1) with oxygen gas (group 16). Electrons lost must equal electrons gained. How many O₂ molecules are used?
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Magnesium reacting with nitrogen (example data)
measurement value magnesium used (g) 1.215 product formed (g) 1.683 magnesium molar mass (g/mol) 24.3 nitrogen molar mass (g/mol) 14.0 Using the table, which formula does the product have, Luz?
- MgN: one magnesium atom pairs with one nitrogen atom
- Mg₂N₃: the mole ratio of Mg to N is 2 to 3
- Mg₃N₂: 0.0500 mol of Mg to 0.0334 mol of N is 3 to 2
A student says nitrogen has 5 outer electrons, so it forms N⁵⁺. Which reply fits, Milo?
- Supported: an atom's charge matches its number of outer electrons, as with sodium
- Not supported: nitrogen reaches a full shell by gaining 3 electrons, forming N³⁻
- Supported: nitrogen is a nonmetal, and nonmetals lose their outer electrons
Group 2 metals (real data, rounded)
element first ionization energy (kJ/mol) magnesium 738 calcium 590 strontium 550 A student says magnesium and calcium are both group 2, so they react at the same speed. Which reply is best supported, Noah?
- Weak: same outer electrons give the same formula, but calcium gives them up more easily (590 vs 738)
- Supported: group 2 metals are the same in each property, since they share one group
- Supported: both lose 2 electrons, so they should react at the same speed with water or acid
Sodium reacting with chlorine (example data)
measurement value sodium used (g) 2.30 chlorine used (g) 3.55 sodium molar mass (g/mol) 23.0 chlorine molar mass (g/mol) 35.5 A student says the masses 2.30 and 3.55 are about 2 to 3, so the formula is Na₂Cl₃. Which reply fits the table, Pia?
- Supported: masses show how many atoms combine in the formula, so 2 to 3 is the ratio
- Not supported: masses cannot help, so no formula can be found from these data
- Not supported: in moles it is 0.100 Na to 0.100 Cl, a 1 to 1 ratio, so NaCl
Element A ionization energies (real data, rounded)
step energy (kJ/mol) first 496 second 4,562 third 6,910 Using the table, how many outer electrons does element A have, Ren?
- 2: the energy rises by about 4,000, which counts two electrons
- 1: the energy jumps from 496 to 4,562 after the first electron
- 3: three energies are listed, so three electrons can be removed
Element B ionization energies (real data, rounded)
step energy (kJ/mol) first 738 second 1,451 third 7,733 Element B is a metal. Using the table, which formula does it form with chlorine, Tala?
- BCl₂, since the big jump comes after the second electron
- BCl₃, since three energies are listed
- BCl, since the first electron comes off most easily
Elements B and D ionization energies (real data, rounded)
step element B (kJ/mol) element D (kJ/mol) first 738 578 second 1,451 1,817 third 7,733 2,745 fourth not listed 11,577 Which element, B or D, is more likely to form a 3+ ion, Zee?
- Both: each table lists a third energy, so each can lose three electrons
- B: its third energy, 7,733, is the largest in the table and so the most telling
- D: energies rise gently through the third electron, then jump at the fourth