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3 years ago

A.explain what is meant by term

Chemistry

1 answer:

mrs_skeptik [129]3 years ago

6 0

Answer:

Explanation:

1. Atomic numbers:

Atomic number is the number of protons in an atom. It is one of the most diagonistic and representative number used in identifying an atom. The periodic table of element arranges elements based on this number.

No two elements have the same atomic number.

Protons are positively charged particles in an atom.

In a neutral atom, the atomic number is the same as the number electrons since electrical neutrality is attained when the number of protons and electrons are the same.
The atomic number determines the position of an atom on the periodic table and it is unique for every atom.

Periodic patterns

These are trends on that can be predicted on the periodic table because they shew regularities down a group or sometimes across the period.

Some of these trends are atomic radius, electronegativity, metallicity, nuclear charge e.t.c

Properties of elements can be predicted using these patterns even before they are discovered.

Physical property shared by Helium, Argon and Neon is that they are all gases. All group 8 elements are called noble or inert gases.

Chemical property of these elements: they are chemically unreactive.

These gases are very stable having complete electronic shell configuration. Every atom on the periodic table tries to attain the state of the noble gases.

Noble Gases/ Inert Gases/ Group O elements

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2 Na2O + CO = Na2CO3 + Na

Vikki [24]

Moles of Na_2O

Given mass/Molar mass
35/62
0.56mol

2 mols Na_2O produces 1 mol sodium carbonate.

1 mol sodium oxide produces 0.5mol sodium carbonate

Moles of sodium carbonate

0.56(0.5)
0.28mol

Molar mass

2(23)+12+3(16)
46+12+48
106g/mol

Mass

0.28(106)
29.7g

8 0

2 years ago

A flexible container at an initial volume of 8.15 l contains 6.51 mol of gas. more gas is then added to the container until it r

kirill [66]

A flexible container at an initial volume of 7.14 L contains 7.51 mol of gas. More gas isthen added to the container until it reaches a final volume of 17.7 L. Assuming the pressure andtemperature of the gas remain constant, calculate the number of moles of gas added to the container.

3 0

3 years ago

What is the percent composition of MgO2H2

zhannawk [14.2K]

41.38 % Mg

55.17 % O

3.45 % H

Explanation:

What is the percent composition of magnesium hydroxide Mg(OH)₂?

To find the percent composition we follow the next algorithm.

First we calculate the molar mass of Mg(OH)₂:

molar mass of Mg(OH)₂ = molar mass of Mg × 1 + molar mass of O × 2 + molar mass of H × 2

molar mass of Mg(OH)₂ = 24 × 1 + 16 × 2 + 1 × 2 = 58 g/mole

Now we devise the next reasoning:

if in 58 g of Mg(OH)₂ there are 24 g of Mg, 32 g of O and 2 g of H

then in 100 g of Mg(OH)₂ there are X g of Mg, Y g of O and Z g of H

X = (100 × 24) / 58 = 41.38 % Mg

X = (100 × 32) / 58 = 55.17 % O

X = (100 × 2) / 58 = 3.45 % H

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percent composition

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4 0

4 years ago

What two elements constitute about three fourths of earth's solid surface?

olchik [2.2K]

The two elements that constitute almost three fourths of the earth's solid surface are oxygen and silicon. Oxygen accounts for 46.6 percent of the Earth's crust, while silicon is 27.7 percent. The next more plentiful element on the Earth's crust is Aluminum.

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4 years ago

Imagine that you wanted to make a time capsule in which you would seal important artifacts from your life (pictures, poems, a lo

Elza [17]

Answer:

Argon gas

Explanation:

Between the options given, argon gas is the least reactive. Argon is known as a noble gas, this means that it is located in the group 18 in the periodic table. These gases are known for their low reactivity, under most circumstances.

The electronic configuration of argon helps us see why that is the case: With an atomic number of 18, it has an electronic configuration of 1s² 2s² 2p⁶ 3s² 3p⁶. This means the most external orbital is filled with electrons, meaning that there are not unpaired electrons able to react with other substances.

5 0

3 years ago