<Tr> <Td> </Td> <Td> 26 </Td> <Td> iron </Td> <Td> Fe </Td> <Td> 50,000 </Td> <Td> 41,000 </Td> <Td> 63,000 </Td> <Td> 50,500 </Td> <Td> 56,300 </Td> <Td> 1,150,000,000 </Td> </Tr> <Tr> <Td> 5 </Td> <Td> 20 </Td> <Td> calcium </Td> <Td> Ca </Td> <Td> 36,300 </Td> <Td> 41,000 </Td> <Td> 50,000 </Td> <Td> 36,500 </Td> <Td> 41,500 </Td> <Td> </Td> </Tr> <Tr> <Td> 6 </Td> <Td> 11 </Td> <Td> sodium </Td> <Td> Na </Td> <Td> 28,300 </Td> <Td> 23,000 </Td> <Td> 23,000 </Td> <Td> 27,500 </Td> <Td> 23,600 </Td> <Td> 255,000,000 </Td> </Tr> <Tr> <Td> 7 </Td> <Td> 19 </Td> <Td> potassium </Td> <Td> </Td> <Td> 25,900 </Td> <Td> 21,000 </Td> <Td> 15,000 </Td> <Td> 25,800 </Td> <Td> 20,900 </Td> <Td> </Td> </Tr>

What are the 2 most abundant elements in the earths crust