|
Chemical aspects
|
| Name (symbol) |
Magnesium (Mg) |
Calcium (Ca) |
| Element category |
Alkaline earth metal |
Alkaline earth metal |
| Abundance |
Eighth most abundant element in the crust of the Earth |
Fifth most abundant element in the crust of the Earth |
| Atomic number |
12 |
20 |
| Valence |
2 |
2 |
| Crystal structure |
Hexagonal |
Face-centered cubic |
| Atomic radius |
0.65 Å |
0.94 Å |
| Atomic weight |
24.305 g/mol |
40.08 g/mol |
| Specific gravity |
1.738 (20°C) |
1.55 (20°C) |
| Number of hydration shells |
Two layers |
One layer |
| Radius after hydration |
∼400 × larger than its dehydrated form |
∼25 × larger than its dehydrated form |
| Isotopes |
Magnesium naturally exists in three stable isotopes: |
Calcium has five stable isotopes: |
|
[24]Mg (most abundant isotope) |
[40]Ca (most abundant isotope) |
|
[25]Mg |
[42]Ca |
|
[26]Mg |
[43]Ca |
|
[28]Mg radioactive, β-decay |
[44]Ca |
|
|
[46]Ca |
|
Physiological aspects
|
| Availability in the human body |
Normal serum concentration range: 0.65–1.05 mmol/L, divided into three fractions: |
Normal serum concentration range: 2.2–2.6 mmol/L, divided into three fractions: |
|
Free, ionized (ultrafilterable fraction): 55–70% |
Free, ionized (ultrafilterable fraction): 47.5–50% |
|
Protein-bound (non-ultrafilterable): 20–30% |
Protein-bound (non-ultrafilterable): 42–46% |
|
Complexed (citrate, bicarbonate, phosphate): 5–15% |
Complexed (citrate, bicarbonate, phosphate): 6.0–6.5% |
| Total body content in adults |
∼24 g |
∼1000 g |
| Function with respect to cell death |
Anti-apoptotic |
Pro-apoptotic |
| Information attained by serum level |
Serum level does not represent total body content |
Serum level does not represent total body content |
