Why cannot #"2-methylpropene"# support geometric isomerism?

Related questions

• Why are trans alkenes more stable than cis alkenes?
• Are #cis# and #trans# isomers examples of diastereomers?
• What are the nomenclature rules to assign cis or trans prefixes?
• How can I draw cis and trans isomers?
• What are cis and trans isomers?
• Why is cis and trans nomenclature important in organic chemistry?
• When can the molecule 2-butene, #C_4H_8#, undergo a geometric change called cis-trans isomerization?
• Why is the #pi# bond between the two central carbon atoms destroyed halfway through the rotation...
• Do either cis-#[3Co(en)_2Cl_2]^+# or trans-#[3Co(en)_2Cl_2]^-# have optical isomers?
• Which compound does not exist 1,2,3,4,5,6,7-octaheptaene, cis-2-butane, trans-3-hexene,...