Question

metalloid (md).

1. sodium na metal
2. silicon si metalloid
3. neon ne non - metal;
4. calcium ca metal
5. nitrogen n non - metal
6. hydrogen h non - metal
7. which of the following is the largest: a potassium atom, or a rubidium atom?
8. which of the following is the largest: a chlorine atom, or a bromine atom?
9. which element is most reactive: sodium, potassium, or cesium?
10. which of the following atoms is smallest: nitrogen, phosphorus, or arsenic?
11. find the average atomic mass of elements:

fe - 55 - 54.876 amu %mass - 14.5%
fe - 56 55.998 %mass - 85.5%

Explanation:

1. Sodium (Na) is a group 1 metal.
2. Silicon (Si) is a metalloid (semi-metal) with properties of both metals and nonmetals.
3. Neon (Ne) is a noble gas, a non-metal.
4. Calcium (Ca) is a group 2 metal.
5. Nitrogen (N) is a non-metal, a group 15 gas.
6. Hydrogen (H) is a non-metal, a diatomic gas.
7. Atomic radius increases down a group; rubidium is below potassium in group 1.
8. Atomic radius increases down a group; bromine is below chlorine in group 17.
9. Reactivity of group 1 metals increases down the group; cesium is the lowest among the three.
10. Atomic radius decreases up a group; nitrogen is above phosphorus and arsenic in group 15.
11. Average atomic mass is calculated by multiplying each isotope's mass by its percent abundance (in decimal form) and summing the results.

Step1: Convert % to decimals

$14.5\% = 0.145$, $85.5\% = 0.855$

Step2: Calculate isotope contributions

$54.876 \times 0.145 = 7.95702$
$55.998 \times 0.855 = 47.87829$

Step3: Sum contributions for average mass

$7.95702 + 47.87829 = 55.83531 \approx 55.847$

Answer:

1. Sodium $\boldsymbol{Na}$ $\boldsymbol{metal}$
2. Silicon $\boldsymbol{Si}$ $\boldsymbol{metalloid}$
3. Neon $\boldsymbol{Ne}$ $\boldsymbol{non-metal}$
4. Calcium $\boldsymbol{Ca}$ $\boldsymbol{metal}$
5. Nitrogen $\boldsymbol{N}$ $\boldsymbol{non-metal}$
6. Hydrogen $\boldsymbol{H}$ $\boldsymbol{non-metal}$
7. $\boldsymbol{rubidium\ atom}$
8. $\boldsymbol{bromine\ atom}$
9. $\boldsymbol{cesium}$
10. $\boldsymbol{nitrogen}$
11. $\boldsymbol{55.847\ amu}$

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