Self-esteem is intricately tied to our perception of competence and our ability to exert control over our lives. One of the primary sources of this perception is performance feedback — the ongoing evaluation of our actions in terms of success and failure. According to Franks and Marolla (1976), people derive self-worth from experiencing themselves as causal agents, capable of achieving goals and overcoming obstacles. This process nurtures a critical component of self-esteem:...

Group 1 elements are soft and shiny metallic solids. They are malleable, ductile, and good conductors of heat and electricity. The melting points of the alkali metals are unusually low for metals and decrease going down the group, while the density increases going down the group with the exception of potassium (Table 1).
Table 1: Properties of the alkali metals

Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Drüde called the “Electron Sea Model”. 

Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3–12 are transition elements. The f-block elements, also called inner transition metals (the lanthanides and actinides), also meet this criterion because the d orbital is partially occupied before the f orbitals.

The amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground state is called its first ionization energy (IE1). The first ionization energy for an element, X, is the energy required to form a cation with 1+ charge:

Chemical reactions, such as those that occur when you light a match, involve changes in energy as well as matter.